You may download Ideal DVD to iPad Converter 1.0.1 from
http://www.idealdvdcopy.com/dvd-to-ipad.htm and install it to have a
try. If you still failed to rip thor, that mostly means your edition
is another one, just keep the DVD in DVD drive, then click the
"configure" button, click "Export ifo files" menu, save the
exported .iba file and send it to their support team, they'll help you
fix it within 1 day.