from roxio's web site:
Dual layer support for recording data using Creator Classic and was added to Easy Media Creator 7 in version 7.0.430.0. In order to record to dual layer media you must also have a drive that specifically supports dual layer.
If you have a version of Easy Media Creator 7 which is lower then 7.0.430.0 you will need to update in order to burn to dual layer media. You may easily update your software by following these steps:
so if you've got Roxio 7 already just update it.