RoleTag.ElementGUID crashes in 831?

[albinofrenchy]

Whenever I make a call to read a role tags ElementGUID, I get this exception:

System.BadImageFormatException: Invalid access to memory location. (Exception from HRESULT: 0x800703E6)
   at EA.IDualRoleTag.get_ElementGUID()

I'm doing everything that is in the help file regarding role tags, so am I missing something? Is this a known defect?

Thanks