I've hit this issue with IRPanels before as well and it just plain "sucks".

Unfortunately, the source code for IRPanels is not available, otherwise, I would have fixed this problem a long time ago. It seems that IR Panels either has a problem with the length of the IR Data for a particular function or the code name itself.

The Runtime Error 5 is an overflow error from Visual Basic but I have not been able to ascertain exactly why the problem occurs.

The problem may indeed be due to the format of the header that is put before the IR Data. In any case, I wish the source code were available as I've hit this problem before as well.

Lyndel