Need Serial Upgrade help Pro 4.01 to 5 to RC 7.21

I wasn't sure what area to contact.
I receive RC for 7.21 but it seems I cant download it. The message says enter serial #. I have a older ver of Mixvibes its Pro 4.02 I do have ver 5 too, but I had to rebuild my computer and haven't figured out how to get back to Ver. 5 upgrade wise. Is that truly my serial number in the properties option off of file on the top menu while inside Mixvibes 4.02
Any help that you can give me in all ares would be very much appreciated
Thegreyhound
I receive RC for 7.21 but it seems I cant download it. The message says enter serial #. I have a older ver of Mixvibes its Pro 4.02 I do have ver 5 too, but I had to rebuild my computer and haven't figured out how to get back to Ver. 5 upgrade wise. Is that truly my serial number in the properties option off of file on the top menu while inside Mixvibes 4.02
Any help that you can give me in all ares would be very much appreciated
Thegreyhound