BookID Problem and Zip Files

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I am trying to import Chartbuster CDG5013 greatest Songs of the Fifties(zip files). There are 3 Disc:
CB5013-01
CB5013-02
CB5013-03

When I import the first disc It shows up as disc ID CB5013 when it should be cb5013-01. I cannot manually change it because the disc id is grayed out. If I import it this way then when I do the second and third disc they over ride the previous import because it keeps using the wrong disc id. It uses CB5013 every time.

I know the correct disc Id numbers are in the database becuase when I call up the import screen and the selection area is still empty, I find Chartbusetr Pro500 in the drop down list and the correct disc ID's listed.