CD-Recordable Kits - FAQs
All files and documentation are offered on an *AS IS* basis and you assume full responsibility for using them.
CD Creator - can't add any more sessions to a disc 
Once audio tracks are on a CD, the session is closed and you will not be able
to add any additional tracks.

Therefore, if you have included one or more audio tracks on the CD, you will
not be able to add any more sessions to the disc.  

Also, if the disc you are trying to import a session to is a mixed-mode CD,
this will not work either.