The program does not work properly within the function of producing an image file. It does not recognize the next DVD (burner Pioneer DVD-RW DVRTD 10RS) and it's constantly repeating a window asking to insert the next DVD even after this had been done. Exiting is the only way out: No backup possible.
The application is using more than one DVD to backup the data. If it asks for next DVD, then you need to insert another compatible DVD. You need to check with the application what storage mediums supports then backup the data.