I keep getting an undefined index notice

Question

I have a form which contains a file input:

 var $fileImage = $("<form action='imageupload.php' method='post' enctype='multipart/form-data' target='upload_target' onsubmit='startImageUpload(this);' class='imageuploadform' ><label>" + 
    "Image File: <input name='fileImage' type='file' class='fileImage' /></label><br/><label class='imagelbl'>" + 
    "<input type='submit' name='submitImageBtn' class='sbtn' value='Upload' /></label>" + +
    "</p> <iframe class='upload_target' name='upload_target' src='#' style='wclassth:0;height:0;border:0px;solclass #fff;'></iframe></form>");

This links to a php script where it uploads the file:

<?php

   $destination_path = str_replace("//", "/", $_SERVER['DOCUMENT_ROOT']."/")."ImageFiles";

   $result = 0;

   $target_path = $destination_path . basename( $_FILES['fileImage']['name']);

   if(move_uploaded_file($_FILES['fileImage']['tmp_name'], $target_path)) {
      $result = 1;
   }

   sleep(1);
?>

<script language="javascript" type="text/javascript">window.top.window.stopImageUpload(<?php echo $result; ?>);</script>   

Problem is that in the php script it is stating I am having an undefined index wherever it states 'fileImage' in the php script. But I don't know why it is saying I am having undefined index when I have mentioned in the name attribute in the form 'fileImage'. Why is it stating I am having an undefined index for 'fileImage' in the php script?

Here is a link to an application where you can append rows which include file inputs, you can test this and see for yourself if you wish but at moment it keeps saying there is an error during uploading. application