ZUNE HELP!! Not able to sync wmv?

So I have been trying to sync a video to my zune 120 and it was originally an .avi file and I had to convert it to an mp4 file because my zune doesn't support avi files. So I did that and I thought problem solved... well no. So then I thought maybe the resolution was to high so I converted it again to wmv this time. The resolution is now 320x240 so I doubt that is the problem. And it shows up on the zune software in my videos but when I try to sync it, it says added one video at the bottom of the screen and then the progress jumps from 0% to 100% but when I check it's not there. What could the problem be??? Im very confused, especially because I could sync other mp4 files to my zune but not the one I wanted to..