Cannot see all available lines on Return form in 11.5.10.2

 When I am performing multi line returns in Oracle 11.5.10.2, I have found that when I enter the first return line (from the top line on the form)along with the RMA# on the Transactions tab and the Comments on the Details tab and then go back to the Transactions tab to enter my second return, the item numbers that were below the line I previously entered are no longer visible. If I enter the form and go all the way to the last line first and perform my return transactions while moving back up the form I will be able