Hi David,
I am sorry to say that DSP/BIOS 5.20 is not supported on CCS 6.0. Would it be possible to migrate your project to the latest DSP/BIOS (5.42.01.09)? I installed and verified that CCS 6.0 does recognize it.
If migration is out of the question; I would suggest you keep the CCS 5.x install you have been using. CCS 5 and CCS 6 can coexist on the same computer.
Regards,
-- Emmanuel