I have UM installed on Suse 11.1.
When trying to play .wav file in UM message: could not load file.
while in ALSAplayer the same file plays without any problem, so I don’t think it a issue of rights. (Also because same error when logged in as root.
How large is the .wav file? There are a few rare bugs when you try to open very large files (2 hours or more). Of course, such files aren’t commonly used by mobile disc jockeys.
Another possibility is that your .wav file is broken. Other players may use other error detection routines.