facing problem in facebook connect api using asp.net

I am using Facebook connect API to grab my friendlist. It redirects me to the login page.

but when I provide credentials it throws an error something like this;

API Error Code: 100
API Error Description: Invalid parameter
Error Message: Requires valid next URL.

Here is the code;

//my actual values are mentioned in the key

_fbService.ApplicationKey = "KEY";
        _fbService.Secret = "Key";
        _fbService.IsDesktopApplication = false;
        string sessionKey = Session["Facebook_session_key"] as String;
        string userId = Session["Facebook_userId"] as String;



        // When the user uses the Facebook 开发者_如何学Gologin page, the redirect back here will will have the auth_token in the query params
        string authToken = Request.QueryString["auth_token"];
        if (!String.IsNullOrEmpty(sessionKey))
        {
            _fbService.SessionKey = sessionKey;
            _fbService.UserId = userId;
        }
        else if (!String.IsNullOrEmpty(authToken))
        {
            _fbService.CreateSession(authToken);
            Session["Facebook_session_key"] = _fbService.SessionKey;
            Session["Facebook_userId"] = _fbService.UserId;
            Session["Facebook_session_expires"] = _fbService.SessionExpires;
        }
        else
        {
            Response.Redirect(@"http://www.Facebook.com/login.php?api_key=" + _fbService.ApplicationKey + @"&v=1.0");
        }

        if (!IsPostBack)
        {
            // Use the FacebookService Component to populate Friends
            //MyFriendList.Friends = _fbService.GetFriends();
             MyFriendlist.Friends = _fbService.GetFriends();
        }

Does anyone knows how to get rid of this? Thanks in advance.

Instead of redirecting to the url, try using

base.login=true;

//Response.Redirect(@"http://www.Facebook.com/login.php?api_key=" + _fbService.ApplicationKey + @"&v=1.0");

or

Response.Redirect(@"http://www.Facebook.com/login.php?api_key=" + _fbService.ApplicationKey + @"&v=1.0&next=http://apps.facebook.com/yourapplication");