When I execute that query in the Query Analyser of SQL Server 7.0 the result is OK but when I exete from VB with RDO the result is something else... why?

Here is the query:

select pd_id, pd_name,
Mnt = (select sum(pr_price) from product_price pp inner join product p1 on pp.pd_id = p1.pd_id where pp.pd_id = p.pd_id) from product p

We know that the inner join is not neccessary but it is why we are getting the error.