Have you tried to "forget" the WiFi network (via the Settings app) and then re-found/re-loaded that network onto your iPad? Have you reset the router (even though it works for the phone, a reset will not hurt and may help the iPad connect).
Or, have you tried a restart or a reset of the iPad to see if that'll work? To do (apologies if you know):
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.
If that doesn't help, try this last step...
Reset: Hold both the power and home buttons until the screen goes dark and the Apple logo then appears (the slide to unlock screen may or may not appear). Once the logo appears, release the buttons. After a time, your homescreen will appear. Please note that it may take some time for the Apple logo to appear or for your homescreen to appear (or both). This is normal. Eventually, the homescreen will appear.
See if any of that helps. Holler back if it doesn't and we'll try something else.
Marilyn