Failed to OpenActiveSession with “an unknown error occurred” at iOS Facebook SDK

Hello,

I'm trying to integrate facebook into iPhone app using Xamarin MonoTouch. I'm using this SDK component: http://components.xamarin.com/view/facebookios

var activeSessionOpened = FBSession.OpenActiveSession(false);
Debug.WriteLine("Active Session Opened: {0}", activeSessionOpened);

activeSessionOpened = FBSession.OpenActiveSession(new string[] { }, true,
    (session, status, error) =>
    {
        Debug.WriteLine("Active Session State Changed. Status: {0}. Error: {1}", status, error.DebugDescription);
    });

Every time during 2nd request to OpenActiveSession I'm getting the following error:

"Error Domain=com.facebook.sdk Code=2 \"The operation couldn’t be completed. (com.facebook.sdk error 2.)\" UserInfo=0x1e081e60 {com.facebook.sdk:ErrorLoginFailedReason=com.facebook.sdk:SystemLoginCancelled, com.facebook.sdk:ErrorInnerErrorKey=Error Domain=com.apple.accounts Code=7 \"The Facebook server could not fulfill this access request: An unknown error occurred\" UserInfo=0x1cdba190 {NSLocalizedDescription=The Facebook server could not fulfill this access request: An unknown error occurred}, com.facebook.sdk:ErrorSessionKey=, expirationDate: (null), refreshDate: (null), attemptedRefreshDate: 0001-12-30 00:00:00 +0000, permissions:(null)>}"

Sample here: https://dl.dropboxusercontent.com/u/19503836/iPhoneFace2.zip

I appreciate any suggestion and help. Thanks!