Lost season 1 disc 6

hi I downladed the trial version of dvdfab platinum. I managed to back up lost to 2 dvds for each disc until disc 6 when i could not choose the option to back up to 2 discs. the only one available was the one to copy to the hard disc without compressing.
Is there something wrong? I tried restarting but there was no difference. what should i do?