My phone won't vibrate

My phone won't vibrate, even though I set it to
vibrate for incoming calls and SMS. I've also tried the vibration mode. Is
there something wrong with my phone?? I'll be thankful for every answer

Invoke the phone and dial *#0*#. You don't have to pick up, it'll go to the diagnostics screen after you type the last #. On the diagnostics screen, touch the "vibration" button. The screen goes black and the phone vibrates. Touch the screen again to return to the diagnostics screen. Touch back to return to the dialing screen.

Edit: Before going to above test, go to Settings -> Sound and Display -> Vibration intensity and make sure the slider isn't set all the way to the left, which disables the vibration even in above test. Set the desired vibration intensity there, then try the above test.

Superb... useful