stored functions and gateways

I want to perform this statement:

select tableA.field, function X(paramter) from tableA_at_YYY

YYY is a remote database (DEC RDB)

In Function X I execute an select on another table of the remote database YYY.

The result is that sql/plus on my client PC shows no action anymore...

When I change the statement in het following sentence I get the result that I expected:

select H.tableA.field, function X(paramter)   from tableA_at_YYY H,

       tableA_at_YYY I
 where H.<primary key> = I.<primary key>

Alas, The join I introduce (I can't explain why this work..), give me problems with performance. Although the primary key is supported by the right indexes on the remote database, when I give an extra where-clause for instance 'and H.<primary key> = 'abcd'', the action by way of the gateway (db-link) will do a full table scan. Conclusion, the gateway does'nt fully support indexes....

Who has a sollution for this problem ?

Ed

We use the following version of oracle:

Oracle 7 server 7.1.5.2.3 on a Dec Alpha with distributed option
PL/SQL 2.1.5.2.0
SQL/Plus 3.2.2.0.1
The remote database is DEC RDB Received on Thu Mar 13 1997 - 00:00:00 CST