download file behaviour not working

I have applied a download behaviour to the following form:

<form method="post" enctype="multipart/form-data" name="file-e" id="file-e" action="" >
<input type="hidden" name="file-name-e" value="<?php echo $row_rsEnquiryDetail['files_e']; ?>">
<button type="submit" id="download" name="download-e" class="btn btn-default btn-xs">Download</button>
</form>

But for not the first time I can not get this to work. Once I click the submit form I just get a screen similar to the screen shot attached. Its possible it might be because of the session value and the recordset ( sql statement ) but this is something I struggle to understand.

I have attached this page ( enquiry-details.php ) and the page that has the links with url parameters ( enquiries-list.php ) that determine the content of the enquiry-details.php page. This page will eventually have numerous download behaviours but I'm only testing the 'files_e' form currently.