Every song must be part of a mix, and must have its own folder. Additionally, every mix must have its own folder. So...
In the songs folder you should have:
1st mix (or mix of coo or whatever)... within that folder you should have the following folders:
song #1
song #2 etc.
Then within each song folder you would have song #1.dwi, song #1.mp3 etc.
If you've got all that sorted out, check log.txt in the part where the songs are loaded up and see if there are any warnings, errors etc.