Got it!
Nevermind, it works with by setting the default value to the hidden field that contains the recordset, not the value directly from the recordset.
Here is the code:
<?php
WA_DFP_SetupUploadStatusStruct("WA_UploadResult1");
if(isset($_POST["Update_x"])){
WA_DFP_UploadFile("WA_UploadResult1", "newhousepic", "".((isset($_POST["housepic"]))?$_POST["housepic"]:"") ."", "".$WA_DFP_UploadStatus["WA_UploadResult1"]["serverDirectory"] ."/images/HOUSEPICS/", "".((isset($_POST["WADAUpdateRecordID"]))?$_POST["WADAUpdateRecordID"]:"") ."".$WA_DFP_UploadStatus["WA_UploadResult1"]["fileExtension"] ."", "0", "".((isset($_POST["WADAUpdateRecordID"]))?$_POST["WADAUpdateRecordID"]:"") ."".$WA_DFP_UploadStatus["WA_UploadResult1"]["fileExtension"] ."", "300", "true", "500", "500");
}
?>
This thread was helpful: showthread.php?t=8829&highlight=update+blank+image