Call transaction question.

In my program I call the transaction FF.9 and made a input there to execute it. Then the transaction if have data return me the amounts and the other information, but if not have data the transaction return me nothing only a sentence that said that not have data.

Ok I need to make a process when the transaction have data but I don't know how can I do that because the massege that I get when the call transaction is maded is if one input field is wrong and not if the transaction

no have data.

So, I need to know in the process of my code if when I made the call transaction of the ff.9, when is executed if the transaction have or not data to make the following process.

Thanks for the help.