What percentage charge is shown in the upper right cornert?
If it is less than 100 percent, and the iPad is connected to its wall charger, something is broken. It could be the iPad, the cable or the wall charger.
The only thing I can think of to try, is to reset the iPad. Hold both the Home and Sleep buttons for several seconds until the Apple logo appears. Ignore the "Slide to power off" arrow. The iPad will restart in a couple minutes. Resetting will not hurt anything, and sometimes clears mysterious problems.
Charging from your computer's USB port may not be reliable, especially when the iPad is awake.