word mail mergers from access

We have recently went to access 2003 from access 97. And from word 97
to Word 2003. We have an Access application we use for ms word mail
mergers to a 5160 mail label format. The data for the Access mdb is
linked to an Oracle db thru ODBC.

There are 2 access union qrys that we use to get the correct field for
the labels. Going thru the 'mail merge' wizard in MS word - we no
longer see those union qrys. (no union qry shows on the word select
data for merge wizard in this mdb) We do see all of the other non
union qrys. We do not see data from some non union qrys. Some non union
qrys we do. Reason why some work and others don't ?
Any suggestions from the ether?