I've deleted the opening and closing form tags, and have this around my download button:
<form class="DetailsPage Basic_Default" id="Results_Basic_Default"name="Results_Basic_Default" method="post" action="<?php echo (htmlentities($_SERVER["PHP_SELF"], ENT_QUOTES)); ?>">
<input type="submit" id="download" value="Download" name="Download" /
<input type="hidden" value="" />
</form>
How am I binding its value again?
Was looking in the properties for a lightning bolt?