ProcessUserAuthorization is always null

Question

I am trying to use OpenIdRelyingPartyWebForms, but the line AuthorizedTokenResponse accessToken = Global.YahooWebConsumer.ProcessUserAuthorization (authResponse); returns null. I am trying to use this project as is, and the only change I made was to change the private const string YahooOPIdentifier = "yahoo.com"; for the private constant string YahooOPIdentifier = "me.yahoo.com" ;. I added all my tokens and secrets.

Project included: http://github.com/yahoo/yos-social-demo-dotnet

Thank!