event.targetTouches[0].screenY gives a wrong value in iPhone 5
<p>I use the following code to get the touch start postition (x,y). It works 95% or more time, but occasionally, I get Y=530 when I touch the middle of screen when y should be 568/2. </p>

<p>Any help or guess why?  Thank you very much.</p>

<pre><code>$('#myDiv').bind("touchstart", function () {
        event.preventDefault();
         startX = event.targetTouches[0].screenX;  
        startY = event.targetTouches[0].screenY;
</code></pre>

<p>}</p>
