Hi
As Contact2 is 1-1 from Contact 1, you do not need to supply match criteria.
Matching on any child table is a two step process:
1. Use the primary key and foreign key information in the Relationships tab to identify child records that belong to the matched parent record
2. Then use any match criteria in the Match tab to select the correct child record
For a 1-1 table, step 1 is sufficient to identify a unique child record, and you do not need to provide any further matching.
In your case, I suspect that the Relationships tab for Contact2 has been changed. Check that you have primary key #RECID and foreign key #ACCOUNTNO
Regards
Admin