I suggest you start over with the Linux install -- at this point you have not wasted much time.
First see if you can recognize thd CD in the finder.
Then, insert the CD and let it spin up and show on the desktop before trying to capture with VPC.
Then do not eject or insert a new CD unless told to do so by the Linux install.
Finally, when inserting the second CD, wait a few moments after the disk appears on the desktop, for VPC to fully recognize that it is a valid CD.
Other than that, get another CD -- the one you have might be defective.