Hi ToNi,
unfortunately, the error message is correct. To convert a VI from one LabVIEW version to another, the VI has to have a block diagram. To avoid this problem, one could password protect the VI instead.
It looks like that that code is now part of the G Toolbox, and the links to it indicate that the toolbox isn't free of charge:
https://secure.element5.com/shareit/product.html?cart=1&productid=187076&languageid=1¤cies=USD,%20EUR
-B2k