title: vkontakte call api method fails
body: <p>I try to call VK method, and it failed with error:</p>
  
  <pre><code>private function deletePost(postId:String):int
          {
              var sigStr:String = FlashVarsVO.user_id + "api_id="+FlashVarsVO.app_id+"method=wall.deletev=3.09bdnOW93DM3Oy5lcSHr4";
              var sig:String = MD5.hash("sigStr");
              var str:String = "http://api.vk.com/api.php?api_id="+FlashVarsVO.app_id+"&amp;method=wall.delete&amp;v=3.0&amp;format=JSON&amp;post_id="+postId+ "&amp;sid="+ FlashVarsVO.access_token +"&amp;sig=" +sig;
              trace(str);
  
          //  sig = md5(viewer_idname1=value1name2=value2secret)
  
              var req:URLRequest = new URLRequest(str);
              var uLdr:URLLoader = new URLLoader(req);
              uLdr.addEventListener(Event.COMPLETE, onComplete);
              uLdr.addEventListener(ErrorEvent.ERROR, onErrorHandler);
              uLdr.addEventListener(IOErrorEvent.IO_ERROR, ioErrorHandler);
  
              return 0;
          }
  
  http://api.vk.com/api.php?api_id=1111111&amp;method=wall.delete&amp;v=3.0&amp;format=JSON&amp;post_id=1629&amp;sid=bf472ebcf2eba19cbdb56d86a8bd477603bbd76bd6c5356e4d003815c7cf3a4&amp;sig=62b1265890d247efdd939f616cad1e8d
  </code></pre>
  
  <p>for this request, vk.com sends me such response:</p>
  
  <pre><code>{"error":{"error_code":4,"error_msg":"Incorrect signature: Session can be expired, revoked by user or connected with different IP address","request_params":[{"key":"api_id","value":"1111111"},{"key":"method","value":"wall.delete"},{"key":"v","value":"3.0"},{"key":"format","value":"JSON"},{"key":"post_id","value":"1629"},{"key":"sid","value":"bf472ebcf2eba19cbdb56d86a8bd477603bbd76bd6c5356e4d003815c7cf3a4"},{"key":"sig","value":"62b1265890d247efdd939f616cad1e8d"}]}}
  </code></pre>
  
  <p>How to make it workable? Anyone faced with such error?? Thanks.</p>