If this were my child, this is what I would do:
#1. Rule out any health or emotional issues first by making sure she isn't sick, having nightmares, or any other need that clearly requires your attention. If none of these seem to be the case, go to step #2.
#2. Let her scream and pound the door. She is probably trying to get your attention to spend time with her. If you run in, it works. Guess what she'll do at the next naptime, in the middle of the night? Keep screaming. She will learn that screaming = mommy's attention NOW!
#3. The previous poster's suggestion of following the routine is outstanding. Follow the same routine with the same expectations and when it is bedtime say good night and let that be it. If she wakes in the middle of the night screaming quickly assess whether or not she truly has a need that requires your immediate attention. If not, let her scream.
I know many people will disagree with me on this, but if she is not sick or hurt then there really is no true 'need' to go to her whenever she screams. If your child screamed because you wouldn't give her five pieces of candy instead of one, I doubt that you'd change your mind and give in and give her more candy. You know she doesn't 'need' the candy; she 'wants' the candy.
Good luck to you and best wishes in finding a solution that fits for your family. If this one is not feasible, then by all means chuck it! Every family is different with differing needs.