Recent Panasonic DVD-RAM drives does not support PD. Only ancient 2.6GB SCSI model (LF-200, approx. $700, 1999) supported PD (I remember that PD is READ-ONLY at LF-200).
I have PD/CD-ROM combo drive, Panasonic LF-1000 SCSI internal model, and some PD medias. PD is soooooooo slow! I will not use PD any more.