Plextor PX-LB950UE burns BD-RE but won't burn BD-R

[rondi]

This is an external burner connected by either esata or usb, I can burn BD-RE rewriteable just fine with no errors (data verified with ImgBurn) using either connection, but as soon as I try to burn a BD-R write once, it fails after writing the Lead-In. Using the latest ImgBurn, the error is:
I 09:22:44 Filling Buffer... (80 MiB)
I 09:22:44 Writing LeadIn...
W 09:22:55 Failed to Write Sectors 0 - 31 - Reason: Power Calibration Area Error
W 09:22:55 Retrying (1 of 20)...
I 09:23:09 Writing LeadIn...
I 09:23:15 Writing Session 1 of 1... (1 Track, LBA: 0 - 9566623)
I 09:23:15 Writing Track 1 of 1... (MODE1/2048, LBA: 0 - 9566623)
W 09:23:26 Failed to Write Sectors 20032 - 20063 - Reason: Write Error
W 09:23:26 Retrying (1 of 20)...
W 09:23:29 Retry Failed - Reason: Invalid Address For Write

I've tried 6 BD-R using various burning programs and using slower write speeds with no change..
Around a month ago, I updated the burner firmware from 1.02 (which I had no problems with) to 1.03 and that is when the problem started. A few days ago I updated to 1.04 and still have the problem. I wish I could go back to 1.02--but I can only find 1.03 or 1.04 for this model.
Any help would be appreciated,
TIA, Ron

 

[rondi]

Since nobody had any suggestions--I bought a new Pioneer BD burner and installed in my desktop. VERY easy to install and it works great. Instruction for the burner said to NOT install it in a portable enclosure --only in a PC chassis, so that's what I did. My guess is--there is not enough cooling inside the enclosure--the Plextor case has on openings. I have a much older, metal enclosure with a fan--but it has IDE connections.