What version of DvdFab are you using? What happens when you don't choose this feature? Are the menu items clickable?
I can help with PgcEdit, but I don't know about the rules of this forum in providing help with other tools, and if IFO and VOB files are allowed to be posted or linked to be downloaded here. You may be better off asking for help in doom9 (and they don't allowed source files to be posted) or in videohelp forum.
On a side note, I run into some problems when testing the 6.1.0.5 beta. When I use the source from the ripped DVD folder on a HD, and the destination folder is another folder on a different HD, clicking on the Start button does not do anything. So when i choose the destination output as an ISO file, clicking on the Start button gives me the process fail message. This looks like a bug to me. It seems like DVDFab wants the destination to be on a DVD drive, but I don't want it to burn. Anyone has this problem?
Another thing I notice is the Change DVD Playback Order option. On some DVDs, this option is disabled, on others it's enabled. It tells me to have Pathplayer enabled, but I already have it always enabled. So what is the reason for the option being disabled on some DVDs? I expect this option to be always enabled (provided pathplayer is always enabled) whether the source is from the hard drive or the DVD drive.