I would recommend a few things.
First restart the iPad.
iPhone, iPad, iPod touch: Turning off and on (restarting) and resetting
If that doesnt resolve it, close all the apps to see if an app is interfering with the operation.
iOS: Force an app to close
Next reset the iPad if the issue persists
Press and hold the Sleep/Wake button and the Home button together for at least ten seconds, until the Apple logo appears.
From: iPhone, iPad, iPod touch: Turning off and on (restarting) and resetting
And finally if needed I would restore the iPad
iTunes: Restoring iOS software