Panasonic DMR-EH50 and Pan. DVD-RAM disks inconsistent

[rehoboth]

Bought a box of 12 individually wrapped discs from supplier in Danbury.

LM-AD240LU 9.4 GB DVD-RAM being used in a DMR-EH50

On the disc itself says Type 4 and CPRM

Within a box, some of these discs
record just fine on both sides. Some record fine on side1 and not side 2

some, even on side 1 just return the message "cannot record on the disc. The video system of
the disc is different."

What would cause this and what can be done?


Thanks

[rehoboth]

Additional note: trying on another machine. If I record side 1 on the DMR-E100H, side 2 then shows "NO REC"
But I open a new disk, and put in side 2 first, I am able to record on it. Maddening!