Error when attempting to generate a target file: Expecting element 'NonTranslatableStyleMappingRule' ...

Hello,

When I try to generate a target file, I get the following error message:

Expecting element 'NonTranslatableStyleMappingRule' from namespace 'schemas.datacontract.org/.../Sdl.FileTypeSupport.Filters.MicrosoftOffice.Core.Common'.. Encountered 'Element'  with name 'NonTranslatableStyleMappingRule', namespace 'schemas.datacontract.org/.../Sdl.FileTypeSupport.Filters.MicrosoftOffice.Common'.

I've followed the instructions at http://producthelp.sdl.com/kb/Articles/9480.html, but the string "MicrosoftOffice.Core.Common" is already present (all four instances).

What else could be the source of this problem?

Thanks,

Hanna