to help troubleshoot the issue, remove the redirect from the insert behavior, change:
$WA_redirectURL = "Detail.php";
to:
$WA_redirectURL = "";
add this code at line 1:
<?php
error_reporting(E_ALL);
ini_set('display_errors','on');
?>
then just before the closing </body> tag add the following code:
<?php
echo("<pre>");
var_dump($_FILES);
echo("</pre>");
echo WA_DFP_AllUploadsDebug();
?>
this will write some debug info to the bottom of the page, please post this information back