this code is the download code:
<?php
WA_DFP_SetupDownloadStatusStruct("WA_DownloadResult1");
if(isset($_POST["downloaddoc"])){
WA_DFP_DownloadFile("WA_DownloadResult1", "assets/files/", "".((isset($_FILES["doc_file"]))?$_FILES["doc_file"]["name"]:"") ."", "[FileName]", false, false, false, "", "", "", "");
}
?>
this is set to use the doc_file file field, not a hidden form element. notice that it uses the file collection;
$_FILES["doc_file"]["name"]
not the post collection
I think i see the problem, and cause of the confusion, in both forms, you have a form element named the same thing. In the first form, it is a file field named doc_file, in the second form it is a hidden element, the confusion comes from using the same name in both forms, use unique names for the elements in each form.