Attach to weapon

I can link and attach objects in 3ds max 6 to the bones in the main model but I am having a problem attaching a new object to the primary weapon. If I try to link it, when I export the cas it comes up with the error

"-- unable to convert: undefined to type: Integer"

If I just attach it and make it part of the primary weapon it comes up with the error

"Mesh Object02 must have the skin modifier at the top of the stack. If it is static then it must have a bone as it's parent"

If I put a skin modifier on it exceeds the vertex count of skin.
I don't know what to try now. Anyone know what to do? ~:confused: