to troubleshoot, edit the update and insert server behaviors so that they do not redirect.
then open the bindings panel, expand the WA Uploaded Files Global Status binding group and add the Debug info binding to your page
next turn on error reporting by adding the following code at line 1:
and dump the files contents by adding the following code at the end of the page before the closing <body> tag:
<?php var_dump($_FILES); ?>
test the upload again and post the results of the debug info and files collection.