You may have run into some movies with advanced protection schemes that DVDShrink cannot handle on its own. DVDShrink has not been updated in many years, and will never be completely effective as a decrypter with these types of movies.
I suggest getting DVDFab HD Decrypter to do the actual decryption/ripping part of the process. It is the free section of DVDFab and is still being updated....it will continue to function even after the trial for the main part of DVDFab expires. You can find it here: http://www.dvdfab.com/free.htm
Once you have the movie on the hard drive, you can open it with DVDShrink to do any compression necessary to fit onto a blank, single layer dvd. Then burn to a disk.