Hi
Can someone explain this to me then? I found it on the help menu.
I don't quite understand the part about that the files must be Mac OSX extended format.
Recording on a recordable disc more than once
Normally, you can burn items to a recordable disc, such as a CD-R, CD-RW, or DVD-RW, only one time. However, if you use Disk Utility to burn the disc, you can burn items to a disk in more than one session as long as space is available. This is also called multisession burning.
In Disk Utility, create a disk image that contains the files you want to burn to the disc.
The files must be from a volume with a Mac OS Extended disk format. To check a volume's disk format, select the disk in Disk Utility and look at the information at the bottom of the Disk Utility window.
Select the disk image in the Disk Utility list and choose Images > Burn.
Select the "Leave disc appendable" checkbox. If you don't see this option, click the triangle in the top-right corner.
Insert a blank recordable disc in the optical drive, and click Burn.
To add more files to the disc later, follow the steps above. You can continue this process until all available space on the disc is used.