Oracle Forms

Hello there

Well i've a form and its having several data block in it and one of the block is master block and the relationships are created accordingly. Now i've added a new block and i am trying to establish the relationship with the master & detail block,but its giving me the error FRM-15004: Error while parsing the join condition,but both the table has the common column,on which the join condition can be made(spelling of the column is correct and at database side the reference key is also established).But still its not working.

Now i tried a dummy form with these two data block and established the relationship, and it worked.But i am wondering why its now working in the previous form.

Please help me out me this ,i am using forms 9i with 9i database.

Thanks in advance,
Bakshi