Not recognising disk

Just got AISEESOFT dvd copy for mac, so far the program works great when coping dvd to dvd, but if i save as an iso file to the hard disk and then try and burn from the file it starts by asking for a disk in the drive then creates a temp file of the iso file{so far so good} but when it comes time to burn it says its waiting for a blank disk without recognising the one in the drive. is there something im doing wrong, has anyone else had the same problem and how did you fix it.