MPEG4 video not playing on iPhone

I have home movies I'm trying to view on my iPhone (16GB). I downloaded some free converters and even purchased one to convert my videos to MPEG 4. I then added the movie to iTunes by click the 'open with' option and selecting iTunes for the movie that were converted. I can even see the movies in ITunes and view through iTunes. However, when I sync the phone it says:

" Some of the songs and videos in your iTunes library, including (converted video file name) were not copied to the iPhone because they cannot be played on this iPhone".

???

Any help is appreciated