Facebook C# SDK 5.1.1 - How to request permissions from user?

I'm trying to request permission for offline access and to post to a user's wall from my application. I am 开发者_StackOverflowable to login ok, but it only requests basic permissions from the user. I've tried removing the application so that it would request permissions again from the user, but that didn't work either.

Here's my code.

     var oAuthClient = new FacebookOAuthClient();
     oAuthClient.AppId = appId;
     oAuthClient.RedirectUri = new Uri(redirectUrl);

     var loginUri = oAuthClient.GetLoginUrl(new Dictionary<string, object> { { "state", returnUrl }, { "req_perms", "offline_access,publish_stream" } });

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I figured it out. Just needed to change req_perms to scope.