//WA_DFP_SetupUploadStatusStruct("WA_UploadResult1");
Martin,
those lines should read
require_once("/WA_DigitalFilePro/HelperPHP.php");
WA_DFP_SetupUploadStatusStruct("WA_UploadResult1");
Dreamweaver will use virtual() instead of require_once() if the Create Links Relative To option is set to Site in your site definition, try changing it to Document