In your store settings, add and change the following tags in your advanced settings field (advset).
<WHPROVIDER>SOPHIOOE</WHPROVIDER>
<WHORDERVERSION>1.1</WHORDERVERSION>
Change the url in the WHORDERSOAPURL tag from this
<WHORDERSOAPURL>http://nexpart.com/WrencheadOrderlink.php</WHORDERSOAPURL>
to
<WHORDERSOAPURL>https://orderlink.whisystems.com:4001/ElectronicOrder.svc?wsdl</WHORDERSOAPURL>
the rest of the tags should be the same.