U3DXT Social FacebookPost not Working?

public void PostOnFaceBook()

 {
     if (CoreXT.IsDevice) {
         Application.CaptureScreenshot ("ScreenShot.png");
         UIImage tmp = new UIImage (Application.persistentDataPath + "/ScreenShot.png");
         // share
         if(_stringPostOnWtitterAndFaceBook == "")
         {
             _stringPostOnWtitterAndFaceBook = "Post !";
         }
         if(_link == "")
         {
             _link = "http://abc.com";
         }
         if(tmp.IsNil)
         {
             SocialXT.Post (SLRequest.SLServiceTypeFacebook, _stringPostOnWtitterAndFaceBook, GameObject.Find("Logo").GetComponent<GUITexture>().texture as Texture2D, _link, true);
         }else
         {
             SocialXT.Post (SLRequest.SLServiceTypeFacebook, _stringPostOnWtitterAndFaceBook, tmp, _link, true);
             System.IO.File.Delete (Application.persistentDataPath + "/ScreenShot.png");            
             
         }

     } 
 }

GameObject.Find("Logo").GetComponent().texture is not null. I'm call thist method from other GameObject. But It not working !. . .