Help...Original disc could not be found or authenticated

I’m trying to back up a software DVD. I’ve tried through Nero 6 disc copy and dvd dycrypter when I inset the copied disc I get the message:
“Original disc could not be found or authenticated.”

It sounds like its searching on the disck before it boots up I can only assume there must be something on the disc its not copied.

Is there any way to get round this problem?

Any help would be much appriciated!