If you are trying to create a DVD (not a bluray) it is better for your source to be an AVI rather than MP4. I don't know if this is the problem, but it would be worth a try. Also be sure your total storage required is not more than a normal DVD disk. The alternate angle has to be re-rendered by DVDA so you need to allow for this video storage as well.
From HELP FILE:
"Any title that contains multiple video tracks will be recompressed when you prepare your project so the main video and the alternate angles can be combined into a new video file. To avoid recompression artifacts (and unnecessary processing time), use AVI files for your multiangle video titles."