Since you are using the File Upload server behavior on the same page. The uploaded file has already been moved from the original upload location.
So instead you have to set the attachment path to the first radio "Entered Value" and use the value:
../EmailImages/<?php echo ($WA_DFP_UploadStatus["WA_UploadResult1"]["serverFileName"]); ?>
That matches the location you have set to move the uploaded file.