PX-712A won't read DVD-R burnt by BenQ DW1620

Problem I have is that my BenQ DW1620 has burnt a disc at 8x (same media as above), used CD-Speed to check disc quality using Benq as reader - very low PIE’s with no PIF’s, files read back ok. However, if I then put this disc into the PX-712A, it cant read it! I can hear the drive spin up and down lots of times, but thats all it does. Do you think I have a faulty drive, or both faulty drives?

PX-712A (fw v.1.05, RCP1 patched) connected to Primary MASTER, pin on MASTER
DW1620 (fw v.B7P9, RPC1 patched) connected to Secondary MASTER, pin on MASTER

Any help would be appreciated. thanks in advance.

My answer is here http://club.cdfreaks.com/showthread.php?t=118808