Updating of data feature in FMP 5.5

I am tearing my hair out trying to make the records which match Last Name and First Name with existing records result in an update of all the data that has been changed.

When I set it up as it seems to indicate in the "books", indicating update matching records in current found set and add remaining records, even when I am importing a minorly altered COPY, so I know there are matching records, it doesn't happen.

I have made First Name and Last Name be the "matching fields" and everything else is straight replace if those match.....

The import whirls and acts as if it is doing what it is supposed to be doing and then BAM, it happily proclaims there are no records that match and none have been imported..... The original records remain the same with none of the data changes I made in the copy.

Can you help me? There must be some FMP 5.5 magic I don't yet!!!;-(

Shoot, there are volumes of FMP magic I don't know yet, but I need this little part now, if possible. Thanks!

Bev