Installer doesnt like my cd

[floam]

Well I just bought the game this morning. I pop in cd 3 and run the 
shell script and it asks for the play disk (I assume this is the first 
disc, though ive tried both) I put in the cd and hit yes and it still 
shows the thing telling me to put in the cd, so I manually umount and 
mount the cd drive, take out the cd, clean it (its brand new no 
scratches), thing is I can do a ls in /mnt/cdrom/ and see everything. 
What could the problem be?