I've been dealing with this mismatch for the last two days, and am at my wits end. We have a development server set up (accessible from the outside), and I am trying to get my OAuth token back from my callback uri. I have my callback set up in my app as just how it is in our environmental configs.

And here is our attempt to reach the service, and the json response...

Am I doing something wrong? or is there some configuration option I forgot in our app?
Here's the Application setup...
