Pioneer DVR-107d & DVD Clone Ver

Can someone explain why my new DVD Writer falls over when used with DVD Clone in a USB 2 External Enclosure. It works great fixed in the computer connected to the IDE cable.
I get this message every time I try and copy something.
(Writing the Video DVD was not successful DVD write error (write DVD 9 ) A DVD write error had occured probly caused by dad media please replace the medium and try again)).
If I use the same medium with Nero burning and the same setup it works great.
I have also tried it with a Pioneer DVD RW DVR-104 ans get the same problem.

Had same problem with Liteon drive in a customers PC. His turned out to be a faulty USB port. Have you tried it in a different one.