The drum maps are to use with a General MIDI synth or softsynth.
I read the material on the Omega. It does not have a built-in MIDI synth. It is an interface only. Most pro-audio soundcards don't have a built-in synth. I have the Delta44 and it doesn't have one either. You either have to use and external keyboard or softsynth.
To use a softsynth is easy: (I'll assume Pro Tracks is like Cakewalk Home Studio) I've never heard of it before, but it says its a Cakewalk product.
On an audio track Right Click on the Fx box, select DXi instruments-Edirol VSC. At this point the VSC panel appears.
On a MIDI track, click on the Out box and select the Edirol VSC.
Now try this with one of the sample MIDI files. It should work.
Sounds to me like your frustration is because you expected to plug it all in and it works. Its not that easy. Its never that easy. You need to read the manuals for the equipment. Then read the Desktop Music Guide
http://www.cakewalk.com/tips/desktop.asp. Then try Pro Tracks. Read the Getting Started section in Help. Then go through each of the Tutorials.
Don't try to do too much at once. Get audio working. Record some audio. Play it back.
Then try MIDI. Record a MIDI track. Play it back.