Q: Movie syncing problem....

Hi, I have an Itouch 3rd generation 32G. and I cant sync my mp4 videos into my Itouch... It plays in the itunes but it wont go into my itouch. I had several movies in my itouch before it got erased but I downloaded the Itunes and upgraded to ios 5.1.1... I dont know, i have some Music Videos that I want to mut in bbut the only problem is that I can not sync them in my itouch 3rd generation. Please help me I converted them to the suitable mp4 for itunes and it still doesnt work....