Sounds like a hardware problem with the keyboard; but in case it is not, try restarting and/or reseting the iPad to see if that helps. Turning the keyboard off then on (if you haven't done so) might also help.
------------------------------
Restart: Hold down the power button until the power off slider appears. Slide it off. When the iPad finishes shutting down, hold down the power button again until the Apple logo appears. Apple recommends you restart the iPad at least once a month.
and then a reset if that does not work.
Reset: Hold down the power and home buttons until the Apple logo appears. The iPad will reboot. This usually takes a bit longer than a restart.