Build a Website

It's a really small project which might be solved in a few minutes and i have been working on for a whole day. I have a asp.net C# web forms website. I want to enable logging in from facebook using owin. It works for google and twitter and works for facebook only on localhost while in production facebook doesn't work. I will send you parts of the code but not all of it and you need to tell me how to fix it. I'll release the milestone only when the facebook integration works. It shouldn't be more than 10$