Make sure you have a namecheck in it and it is named as your addon should be.
Weapon_revolver <Or whatever it is called.
If you use milkshape, you need to make sure the LOD on the export menu are all zero. If not, make sure in the groups tab that there are no names that are the same or have a number AFTER the name. That will screw it up ingame.
(Also, in server.cs, make sure it executes your weapon.cs.