You need to add netmis line, which is supposed to be in maps readme, but in most cases it isn't (old procedure included mapadder.exe which is not used anymore). In either case, open netmis.txt from your main Bz folder and add given line from readme or write your own if you can't find it.
If, let's say, you donwloaded Intimida.zip, unzip all files in addon and check if its bzn name is "Intimida". If it is then do next:
multdm61.bzn multdm61.des 4 8 multdm61.vxt D Stomp
Intimida.bzn Intimida.des 4 4 Intimida.vxt S IntimidaIt may not be the right data, but it ain't wrong either. It'll work.
