[Surgeon]

create a folder called maps in your mohaa/main folder. Then create 2 more folders in the maps folder: Name one dm and the other obj. If your map is sp put it in the maps folder. If its deathmatch or teamdeathmatch put it in the dm folder. If its an objective map put it in the obj folder - then try what JV said..if you've done all this and it doesn't work send the .bsp file to a mate to check if it works on his pc.