Try/Catch/Throw and iss problem. Please help!!?

I am trying to read in several lines, each should have exactly 5 pieces of data. I am using try/catch/throw to determine if the data is in the correct format, and trying to use iss to separate the parts. This is my first time using both, and I am missing something obvious. Firstly, by debugging, I found that the first piece of data is being checked in the second case, giving me errors. I believe I may need to read in more from the iss>> than just the one, but I am lost. Any suggestions?? I would post my code, but it won't give me enough space!