While Dobies are very intelligent, they are also very sensitive and have an aversion to change. If you have a toy, you might go outside and open the door and call her to you with the toy. She needs to get used to it and understand that it won't hurt her. I used to board my dogs at a kennel that had the flaps between the inside and outside, and of course once a dog sees other dogs going out theirs, it's not big deal to them any more.

If you have a friend who has a dog that uses a dog door, you may see if you can get Raven accustomed to the other dog and then use that dog as a "bell cow" to lead Raven through the door. One of the things I have an easy time with on my dogs, is that the new young ones learn from the old timers.