BatchDPG - MP4 Trouble.

I recently downloaded BatchDPG 1.3, AviSynth 2.5.7 and ffdshow.
Trouble is that my BatchDPG only converts AVI. When I try to convert MP4, it tells me to go into a Media Player and take note of the message.

DirectShowSource: Could not open as a video or audio.
Video returned: "DirectShowSource: couldn't open file C:\Documents and Setting\Administrator\Desktop\<Video>.mp4:
Cannot play back the file. The format is not supported."
Audio returned: "DirectShowSource: couldn't open file C:\Documents and Setting\Administrator\Desktop\<Video>.mp4:
Cannot play back the file. The format is not supported."
(C:\Documents and Setting\Administrator\Desktop\<Video>.mp4.avs, line1)

Help is much appreciated.
Thanks.