No MultiTrack Mode possible – why?

Thank you for bringing up the idea of removing the parenthesis. But the situation went worse after that. After removing the parenthesis – whether removing the full (0001) or just the brackets () – the file is not playing at all anymore. The PLAY button stays green (as it would play the file) but no playing of the file (counter stays at 00:00:00 and everything else is blocked. Also Pre-LoadingSong is failing (showing at the display).
Anyway the parenthesis is added to the fie by using the uTool. It is not our regular filename convention. The regular file is just called Pirates 123bpm.wav.
Following up on your idea that the filename may be causing the problem I also removed any spaces. But no luck as well. Regardless what I do, the uTrack24 stays in Stereo Mode (or does not play at all if I tamper with the filename convention).
Forgot to mention: I am on OS X Yosemite, if that may make a difference