filter data on form

[virginie]

hi!
i have a form where i choose according to which fields filter a second form
i did:
Case 3
stLinkCriteria = "orders.supplier = '" & txtSupplier & "'"

the problem is that i want to filter my form per supplier like i did
but i want to filter the records where the field " payment_date" is not null too.
it means i want to display all the orders per supplier chosed that are not " closed" yet, that have to be payed.


my problem is that this "payment_date" is a field from a subform, "order_details", the lines for this order.
so i have n fields " payment_date", one per line in the order.
i have to check if:
if for a specific order to the supplier choosed, ALL the lines in the order are payed and filter them to show only the orders that have 1 or more lines in the details that are without "payment_date"yet.

how can i do that??

how can i change my filter:
stLinkCriteria = "orders.supplier = '" & txtSupplier & "'"
to display only those??