Hello mvb63
Something similar happened to me, running TMG UK Gold Edition 6.12. When I added a husband and said Yes to "create a married name", I got:
Data Type Mismatch
94 TMGAPPROBJ.MINSERTTMGNAME
After about 4 clicks on Ignore, the action seemed to complete.
Then I added a Marriage of two existing people in the database, said Yes to "create a married name", and had the same experiance.
If it happens again I'll check back here.
John