Focusing my camera will not focus when i press the shutter button half way down. the green light indicates the subject is in focus but it is not please help me

I don't know what your perception of proper focusing is.
If there is enough light and enough contrast in the subject you want sharp (in focus) on your picture, you only have to point the camera to the point you want in focus on. Then you press the shutter release button half and wait till the camera is in focus. This is indicated by the focus point on top of the screen. as long as you keep the button half way down, you can move the camera and the focus will not be changed. So you can make changes to the composition. Then when you press the button down complete the picture should be sharp, where you focused on.
Don't try to make a picture, by pressing the button complete. as quick as you can, because the camera won't react as fast as a DSRL.

Most digital cameras have an auto focus function, to activate the auto focus press the shutter button half way down until the you get a green light or indicator then press the shutter button the rest of the way down.

To focus on your subject, lightly push the shutter button (the button you use to take pictures) only half way down. When you push the shutter button half way down, this auto-focuses the camera and you can then fully press the shutter button to take your picture.

This issue can occur in the following circumstances:
The subject is too close to the camera lens Insufficient lighting Subject movement Camera movement Incorrect camera settings Incorrect camera operation Follow the steps below to help prevent taking pictures that appear blurry, out-of-focus or distorted.

If the camera has both an auto focus and manual focus mode, make sure it is set to auto focus. Make sure there is enough lighting to allow the camera to focus on the subject. Make sure the camera settings are set appropriately. When taking close-up or macro-type shots, ensure the subject is not closer than the minimum focus distance of the lens. Also, if the camera has a zoom option, set it to the W (wide-angle) position. If you have a fast-moving subject and the camera has a Program AE mode with a higher shutter speed (such as Sports action), make sure it is enabled. Also, if the camera has an ISO control, set it to a higher setting. If your camera has a SteadyShot/anti-blur function, ensure it is enabled. Aim the camera at the subject. Press the shutter button halfway down. NOTES:
Pressing the shutter button halfway down allows the camera to focus automatically. A flashing green indicator will be visible in the LCD or viewfinder. When the indicator stops flashing, focusing is finished and the camera is ready to take the picture. Some camera models have a Monitoring AF setting that can be selected which allows the camera to focus without the need to hold the button halfway down. Consult the instruction manual of the camera for information whether or not this is applicable for your model.

TTTTTTTTTTTTTTTTTTTTTTTTITf correct focus cannot be obtained
When the subject to be focused is not on the AF target mark (not positioned
in the center of the composition), you can use the following steps to obtain the
correct focus on the subject. This operation is referred to as "focus lock".
Determine the position of the subject after focusing (Focus Lock)
1 Press the power switch.
• The camera turns on in the shooting
mode.
• The lens extends and the monitor turns
on.
• The orange lamp lights.
2 Turn the mode dial and select a
shooting mode.
"Shooting mode" (P.36)
3 Position the AF target mark on
the subject you want to focus on.
• When shooting a hard-to-focus
subject, point the camera at an object
about the same distance away as the
subject.
Press the shutter button halfway
until the green lamp lights.
• When the green lamp lights steadily,
the focus and the exposure are locked.
• When the green lamp blinks, the focus
and exposure are not locked. Release
your finger from the shutter button, reposition
your subject and press the
shutter button halfway again.
5 Keeping the shutter button
pressed halfway, recompose
your shot.
6 Press the shutter button fully.
Try the above, info from D-535, C-370 and X-450.
I can email you the complete manual if this works.
Regards
Phillip

There are two stages to the shutter release. The first stage is the focus stage pressed half way down and the second stage is the actual shutter release. Always press the shutter half way to get the camera focused first then press all the way down when the camera is ready to take the shot. Check to see how the settings are with regard to how it focuses (9-point, face recognition, etc). When the camera focuses you should get a green box or multiple green boxes depending on your settings. That tells you the camera is ready to take the picture. Pressing the shutter all the way down at once from the beginning will cause the pause you describe since the camera has to first focus then shoot the picture. Depending on the subject or subjects the camera may take a second or two longer to focus. With good lighting my G9 focuses pretty fast. Hope this helped.

This depends on which Autofocus system that particular model uses.  Then manual should tell what is happening there- there is usually a more comprehensive manual on the supplied CD.
Failing that speak to the user support of you particular model

I have the C740, which I believe works very similarly if not identically. Unless you have the camera in full time auto focus, I don't believe it actually focuses on the subject until you've pressed the shutter button half way. Until then, the subject may look in focus in the viewfinder, but is not. When you fully depress the shutter in one motion (rather than pressing half way first), the camera will attempt to focus before it takes the shot. If you are not careful about camera movement, you may inadvertently be focusing on something other than what you intended. My camera (and it seems all digicams) has trouble focusing in low light, so you definitely want to use the half press in such situations. Even then, I don't always get the focus correct. Thank the digital Gods for instant feedback! Personally, I almost always use the half press method. To get the 740 in manual focus, you hold the "OK" button down until you see the viewfinder display a focusing scale. It takes a second or so. You should also see "MF" and "AF" designations in the lower left corner of the viewfinder when the scale displays. Use the left and right arrows to select the focus mode you want (i.e. MF or AF), then use the up and down arrows to adjust the focus distance. You'll notice that the area you are focusing on is enlarged when you use the up and down arrows.

You are expecting too much for any auto mode. When shooting under low light conditions, the camera may take longer to achieve focus lock. If the subject is moving too, it will take even longer to lock focus. Try using manual focus for the conditions you described.

You are expecting too much for any auto mode. When shooting under low light conditions, the camera may take longer to achieve focus lock. If the subject is moving too, it will take even longer to lock focus. Try using manual focus for the conditions you described.