Dvdfab-1.91 doesn't work

ok, i want to split a dvd9 into two dvd5’s and keep all the menus etc. i hear dvdfab is the program for this. only problem is it doesn’t work. when it gets to the point in the wizard to choose a chapter to split on, there are no chapters to choose from, and i can’t continue. this only happens for some dvds, for others it works fine.

whats going on?

thanks for the help.