Hello,
the TCITEM structure in use by MASM32 SDK 10 doesn't use the 4.70 control names of the structures properties. http://msdn.microsoft.com/en-us/library/bb760554(v=VS.85).aspx
Additionally, the mask property is named imask, probably to avoid conflicts with MASM. I didn't see this documented though.
Just 2 hints!
Best
Lars