How do I get my dog to use the doggie door? She’s afraid of it.

We have spring loaded doors on our kennel runs and I toss treats through and gradually help the dog less and less until they are pushing on the door and going through on their own. If she won't do this, get a second person and each of you call her back and forth and reward with a really high value treat each time. Let her get frustrated enough to push on the door, once they realize they can do this it doesn't typically take them long to start using the door.