Thanks Marco and Eric,

but how can I access fields which aren't fields but parameter, e.g. I
have a select statement like this:
Select B.BookID, P.BookPub, A.BookAuthor, B.BuyDate from tabBooks B
join tabPub P on tabBooks.PubID=tabPub.PubID join tabAuthors on
tabBooks.AuthorID=tabAuthors.AuthorID where BookAuthor=:BookAuthor
and BuyDate=:BuyDate

The table Books is the detail table of the authors table, so whatever
is shown in my detail table depends on the author shown in the master
table, so far not a problem, but how comes the date into play now?

The example with the books and the select query I just made up, so
don't try to read too much into it. My actual tables are somewhat
more complicated but the problem remains the same.

Florian