My bad...
I posted the wrong href wrap code - should have been:
$WA_MailObject = WAUE_AddAttachment($WA_MailObject,"<a href=".$WA_DFP_UploadStatus["WA_UploadResult1"]["serverDirectory"]."".$WA_DFP_UploadStatus["WA_UploadResult1"]["serverFileName"] . ">" .$WA_DFP_UploadStatus["WA_UploadResult1"]["serverFileName"] . "</a>");
It still doesn't work...