Painful: Databound form not working properly

I just don't get it!

I have a form which is bound to two user defined tables @PAYM and @PDED. These tables are related (or supposed haven't figured if they are really yet)

the forms has text boxes and a combo box bound to table @PAYD and a Matrix bound to table @PDED.

When I browse through the records the only data showing on screens are everything but the Matrix. If the Matrix is bound, isn't it supposed to show the related fields of table @PDED?

And if I use a user data source, do i have to code everything from the ADD and UPDATE actions to the FIND. Doesn't SAP B1 handle this?

I've been trying to make one single form work properly for over two weeks now ... without any luck !