My dog will not come in the doggie door!?

We recently purchased and installed a dog door. Our dog will go out the door to go pee or to play or whatever, but she will not come in. It is not that she doesn't wnat to come in either, she will whine at the door and scratch at the door but she will not come in. We have given her treats, poke our heads out to call her, open the flap for her, etc... But nothing is working for her. Any suggestions or ideas to why she goes out but doesnt come in would be great! Also if you have any ideas on how to fix this problem! thanks :)