So what
do you see in the New Drum Map dropdown? Every map except the Addictive one? If that's the case, I think the filename extension must be wrong.
EDIT: Hmmm, no, just checked and that wouldn't account for not seeing it; it would just fail to load. Seems to me something must still not be right with paths. The path specified in Preferences is the only place it needs to be. Time for some screenshots, maybe.
EDIT 2: Have you restarted SONAR? I just figured out that it caches what's in the Drum Maps folder at startup. If somethings not there at startup, you won't see it. And the file extension *does* have to be correct. That's why I got the error with the wrong extension; SONAR had cached the link, but could no longer load it. After restarting SONAR the mis-named drum map was no longer visible. So need to do both; verify the file extension, and restart SONAR.