[node:204] is a good read if you haven’t gone through it yet.
Make sure your application record here on dev.twitter.com has a URL in the callback field. It doesn’t need to be the URL you’ll use in your app itself, but it needs to be there. Try http://placeholder.com if you don’t know what else to put but you need something valid here in order to dynamically set a callback in the next step.
Then in your code, set the explicit oauth_callback that you’re wanting to use. It should work, provided your networking environment and all else is correct.
