To do that I should send to you all the project! Which is not possible!
that I understand but my point is that cause and effect are seemingly unrelated
IF I DO NOT INVERT THE BYTE VALUE THE CRC RECEIVED IS CORRECT IF I DO INVERT INVERT THE BYTE VALUE THE CRC RECEIVED IS ALWAYS 253!
I don't doubt this is occurring for you but I believe the real cause is either elsewhere or that pbp has a major flaw . you can of course ignore this but it means your project may infact still have a flaw in it than will resurface some point further on . it should not be too difficult to simply paste together the relevant sections of you project code to demonstrate the failure point.