Having trouble adding mp4 to ipad2

I had an avi file that I converted to an mp4. I added the mp4 to iTunes and it appeared in the video section working perfectly. When I added this file to my iPad through itunes it appeared in the video section but was greyed out. iTunes did not appear to be syncing, but I couldn't get this file to play. I have disconnected my iPad from iTunes, but I can not find this file on my iPad.

Please help, I've no idea what I'm doing wrong! Can mp4 files be played on the iPad 2?

Thanks!