MP4 & MOV don't load in JUKE

Hello,

The discription from your Juke page says that
Juke can play MP4 and MOV video files.

But I can not load any MP4 or MOV file in to Juke.

The only video files i can load in Juke are:
MPEG, AVI and WMV files.

Can you please tell me what I'm doing wrong?
Or must I load some other CODECS for these
files to read and play in Juke?

I have WINDOWS XP on my computer and in all other
players like MPC and VLC these file plays whitout
a problem.

Thank you in advance, Salleke.