No pictures when in autofocus mode

Do you have the aperture ring turned to "A"?

Did you ever get a solution to this? I have exactly the same problem only mine is the D40 not the X.

That lens is not an AFS type lens. The D40x camera only uses AFS compatible lenses. You could still mount and use it in M, but it will never give you autofocus or TTL flash.

The D40x only autofocuses with the latest AF-S (and old professional AF-I) lenses. Most traditional (screw-type) AF lenses from 1986 through today will not autofocus on the D40x. If your lens says "AF-S," you're fine.
Most lenses sold today for the D40x are AF-S, and so is the included 18-55mm kit lens. Many non-Nikon lenses from Tamron, Tokina, Quantaray, Sigma and anyone other than Nikon still won't autofocus on the D40x. Try before you buy, but honestly, there isn't much the included 18-55mm lens won't do.
Autofocus systems are fast, but not usually instantaneous. You have to hold the shutter down halfway as you compose the first shot so the AF system can focus and lock, and then the camera fires instantaneously when you press the shutter the rest of the way. See Preventing Shutter Delay for more.

if you're using D40/X, make sure that the attached lens has built-in autofocus motor (e.g. code AF-S for Nikon, HSM for Sigma), because the camera does not have built-in autofocus motor in the body so only manual mode will work in most AF lenses..

if you're lens is already one with built-in autofocus motor, you might need to check the motor at a service center

We tried the same lens on another Nikon (D90) and auto focus did not work.
We mounted a new set of lens on the original D40x, and it worked.
Turns out the 2 year Nikon lens (18mm-135mm) was bad. Nikon lens have a 5 year warrantee. The lens will be sent back to Nikon with no service or shipping charge.

Thanks,
K

Look on the left side of the lens. Make sure the button is on A for auto focus and not M for manual. OR not stuck in the middle. Hopefully that will solve the problem.

Try removing the lens and then reloading it.   Hope this works.

Here is Nikon's specs of lens compatibility for the D40X:


Compatible Lenses*: Nikon F mount with AF coupling and AF contacts Type G or D AF Nikkor:
1) AF-S, AF-I: All functions supported;
2) Other Type G or D AF Nikkor: All functions supported except autofocus
3) PC Micro-Nikkor 85mm f/2.8D: Can only be used in mode M; all other functions supported except autofocus
4) Other AF Nikkor*â¹/AI-P Nikkor: All functions supported except autofocus and 3D Color Matrix Metering II
5) Non-CPU: Can be used in mode M, but exposure meter does not function; electronic range finder can be used if maximum aperture is f/5.6 or faster
6) IX Nikkor lenses cannot be used
*â¹ Excluding lenses for F3AF

They do not recommend 3rd party lenses, ever

check for dust specks on the lens glass.