create data relation

i am trying to make a relation between two tables.
i get this error when i add the realtion to the dataset: "ForeignKeyConstraint requires the child key values(...."
i think i need to set some kind of key column for each table? how do i do that? i have two tables with one column each.

Try to mimic this example . I'm not sure what's your problem but is there any relations between these two tables ?
http://www.vbforums.com/showthread.p...hreadid=253655