Drop event catching

I am having problems with drop event catching with the html5 drag and drop.
I am trying to listen for when an image is dropped into each seperate dropzone. I have an id for each dropzone & their value must go into the corresponding table field in database. I can't get each specific dropzones to listen for the drop event.

Please help if you can, thank you.

HTML Code:

---

<ul id="images">
  <li><a id="img1" draggable="true"><img src="images/1.jpg"></a></li>
  <li><a id="img2" draggable="true"><img src="images/2.jpg"></a></li>
  <li><a id="img3" draggable="true"><img src="images/3.jpg"></a></li>
</ul>




//dropzones


<div class="drop_zones">
  <div class="drop_zone" id="drop_zone1" droppable="true">
  </div>

  <div class="drop_zone" id="drop_zone2"  droppable="true">
  </div>

  <div class="drop_zone" id="drop_zone3" droppable="true">
  </div>
</div>

---

Code:

---

var oldThis = this;

setTimeout(function() {
    oldObj.parentNode.removeChild(oldObj); // remove object from DOM

    // add similar object in another place
    oldThis.innerHTML += '<a id="'+iObj+'" draggable="true"><img src="'+oldSrc+'" />    </a>';

    // and update event handlers
    updateDataTransfer();



    var http = new XMLHttpRequest();
    var url = "post.php";
    var params = iObj;

    http.open("POST", url, true);
    http.onreadystatechange = function() {
          if(http.readyState == 4 && http.status == 200) {
              alert(http.responseText); }

}
http.send(params);



    oldThis.style.borderColor = "#ccc";
}, 500);

return false;
});

---

PHP Code:

---

<?php   

$sql="INSERT INTO table_answers (drop_zone1, drop_zone2, drop_zone3) VALUES      ('$_POST[drop_zone1]','$_POST[drop_zone2]','$_POST[drop_zone3]')";  

if (!mysql_query($sql,$db))  
{  
    die('Error: ' . mysql_error());  
}  

echo $_POST["drop_zone1"];   
echo $_POST["drop_zone2"];   
echo $_POST["drop_zone3"];   

?>

---