You are jumping around the subroutine upon start up right? If your software is verbatum to what you posted then you need to add Goto Start just before the CRC8: label and place a Start: label before your testcode comment. I'm not sure what PBP will do with variables declared after coding starts but I would move the TestData VAR Byte(8) up to before the subroutine where the other declarations are.

Again, I'm away from home for a couple of days so I can't test the code.....