Auto focus confirmation little green dot is blinking

Switch the lens to "M" and focus manually, then take the photo.

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There are several contributing factors to this problem and I'll try to list a few that may be the cause.
All Canon EOS camera auto focus modes us contrast to focus this means simply that no contrast there is no focus. There is a small green dot in the lower right corner of the viewfinder that will come on and stay on solid when auto focus as been achieved. By default the shutter will not operate "click" if auto focus has not been made.

Here are a few examples of where auto focus will ether search (focus back and forth) or fail completely.

A solid painted wall, glass between the camera and subject, mirror, chrome, any large body of water, clear sky. Another place you wouldn't expect is clear skin in your subjects face or body.

Cameras with multiple focus points and set to other then the middle will have a problem if the photographer is still attempting to use the center focus point.

Look for the green dot in the lower right corner of the viewfinder that's your focus confirmation.

A few suggest about this problem. First in manual or auto focus mode does the green in focus confirmation light come on in the lower right corner of the viewfinder? Are you shooting in One Shot-AF, have you selected an Auto Focus Point are your pictures in focus? I know you've been using this camera for 2 years and these questions you need to ask yourself. If that green confirmation light comes on then the picture will be in focus. a few things that will mess up focus are little or no contrast. No contrast like huge expanses of water, sky, glass or infinity will render a auto focus system near useless. Something that is good is that you haven't said anything about error codes which is good. These questions my sound lame but ask yourself this when was the last time I cleaned the lens (Front Element) use a lens cloth for this and huff on it if a little moisture is needed. Do you change lenses often and when was the last time you checked your sensor for dirt? If you have had the lens off you should check the rear lens element for finger prints or oil. A dirty rear lens element will cause everything to look as if it's shot in a dream world. Check your camera sensor buy taking a (manual) focus shot of a piece of clear blue sky download it to the computer increase the size to 100% and check out the blue for dirt. A camera that's two years old and used "normally" may need the sensor cleaned. But go back to this infocus light if it's coming on and the pictures are out of focus then you have another problem as in dirt.
Hope this was a little insight into your problem

The 9 you see is the maximum "burst" which is (pictures made in rapid succession) and is not an issue with your problem at this time the flashing green dot is the in focus confirmation light and it's good that you are seeing this as we will use it to remedy the problem.
Diagram


Manual focus switch
Diagram here

What I want you to do is put the AF-MF switch in the manual mode if it's already in manual mode then that was your problem switch to AF and go take some pictures. If it's in AF mode switch to MF make sure teh camera is on and look through the viewfinder at a subject say 15 feet (4.5 meters) away something that has contrast then turn the manual focus ring on the camera slowly until it appears to your ey that it's coming into focus when it's in focus the green light will come on solid, now you know what you are looking for focus an several different objects at different distances and focus manually. Now switch the lens over to AF (auto focus) and focus on the same thing but let the camera do the focusing What auto focus will not focus on in something with little or no contrast like water clear blue sky a painted wall mirror chrome glass and a few other things.
Here is another diagram to check make sure you are in the correct mode.
Diagram

Now for the focus point in the viewfinder make sure it's in the center position.

To adjust the focus point do this

Once you have the camera set to the center focus point and the correct AF mode (one shot) auto focus should return to your camera. Have fun Robert from London Ontario Canada

Hope I can help with some input to your problem. Let me suggest please that you switch the "mode" dial to "P" for program, check your ISO (I personally shoot ISO 100) and set it for a speed ISO 400 or lower. Most DSLR's use contrast to focus so a mirror, chrome, flat body of water, painted wall especially a white wall are just terrible to get an auto focus on. Also auto focus isn't going to happen in darkness unless you have (for Canon) an external Infrared auto focus assist beam. Also you could be to close to your subject as in attempting to do close up or macro photography and have over extended your lens capabilities.

You aren't doing anything wrong it's just I think that you have fallen into one or all of the above situations that auto focus just can't read being either dark, lacking contrast, or reflective surface or to close to your subject.

I wanted you to get off the full auto so you could enjoy the Rebel and expand on its features shooting in full auto turns it into a very expensive point and shooter. Shooting in "P" you can do what is called Program shift where you actually input settings into the camera before the picture is taken.

That little green dot focus confirmation will work even in manual mode so even though it might look out of focus to you if that dot is green and solid not blinking then it's in focus squeeze the shutter make the shot.

One other bit of information make sure you shut the IS off before mounting the camera on a tripod. if left on it will actually cause more vibration (that took me a while to figure out) have a great day hope this was a help sorry it took three days for me to find you with this problem Robert in Canada

Okay looking at the back of the camera where the viewfinder eye piece is right side upper corner you will see a small wheel partially covered by the rubber rim of the viewfinder by the side of it you will see a small line with a + and - that is a diopter that actually tunes the camera viewfinder to your shooting eye. Pretty fancy eh? Anyway what I do is set the camera in auto focus and focus on an object in a brightly lit room and when the little green light come on in the lower right corner of the viewfinder which is the auto focus confirmation light start turning this wheel one way and another until the image you see come into sharp focus. I don't know about you but I need about three clicks to the + side before everything looks sharp.

This is a fairly new Digital camera model. A few quick things that could cause your particular problem is that the camera hasn't had a media card installed. The media card may not have been formatted to the camera. The lens is not totally locked in position. Within the menu there is a function that prevents the camera from taking a picture if there is no media card installed. If there is a media card in the camera it may be full of pictures and unable to store any more images. If the media card is not the problem then I would say that the camera is not focusing and without focus the camera will not take a picture. Look for the auto focus confirmation little green dot in the viewfinder it should be a solid green not blinking. Hope this was a help

There may be a few things preventing the camera from taking a picture. I don't know the lens you are using but by chance does it have an auto/manual switch that has been switched to manual? Also make sure the lens is locked in position. The camera won't take a picture unless it has focus in the auto focus mode, this is normal. What are you trying to focus on? The camera auto focus system will search and fail to auto focus on surfaces that have little or nor contrast. For example glass, chrome, a blank wall, water, blue sky. Other conditions that auto focus fails is being to close to your subject, heavy fog, a dim lit subject, available light and night photography. Once the little green confirmation light comes on the camera has focus and will operate as it should.

it won't take the picture until the focus is not confirmed (big dot lights up in the lower right side of the viewfinder) even though the button is pressed all the way down.
tamron lenses are notorious for slow (noisy) auto focus, so you have to be patient when focusing and half press repeatedly several times before it locks down, confirmes the focus and takes the picture.

the flashing green dot is caused by the camera not able to focus, and is typically from the following:

1. not enough light - if you are in Aperture Priority, try increasing the ISO
2. low contrast subjects - the camera can't find a good point to focus on
3. overlapping near/far objects - again, the camera can't decide which one to focus on
4. Repetitive patterns

You can go into manual focus, or, auto focus on something the same distance away and lock the focus and shoot.