title: how to remove the exception, System.InvalidOperationException?
body: <p>code is given below </p>
  
  <pre><code>Queue&lt;int&gt; queXpTrackerX = new Queue&lt;int&gt;(10);
  Queue&lt;int&gt; queXpTrackerY = new Queue&lt;int&gt;(10);       
  
  if (iCounterForXpTrack &lt; 10)
  {
      queXpTrackerX.Enqueue(X);
      queXpTrackerY.Enqueue(Y);
      iCounterForXpTrack++;
  }//End IF
  else
  {
      queXpTrackerX.Dequeue();
      queXpTrackerY.Dequeue();
      queXpTrackerX.Enqueue(X);
      queXpTrackerY.Enqueue(Y);
  }//End else
  
  for (int indexXp = 0; indexXp &lt; iCounterForXpTrack; indexXp++)
  {
      gXpTracker.DrawEllipse(Pens.Cyan, queXpTrackerX.ElementAt(indexXp) , queXpTrackerY.ElementAt(indexXp), 5, 5);
  }//end for
  </code></pre>