Why do I keep getting "Cancelled: Transaction not allowed"?

I have been working on the Hosted Tokenization example: https://developer.moneris.com/Documentation/NA/E-Commerce%20Solutions/Hosted%20Solutions/Hosted%20Tokenization

And I have it working, I get an approved code with a data_key. Next, I am trying to convert the Temporary Token into a permanent Vault Token by following these steps: https://developer.moneris.com/Documentation/NA/E-Commerce%20Solutions/Hosted%20Solutions/~/link.aspx?_id=DA303DE370864B50BC167309D103EB6C&_z=z#vaultaddtoken

I have pretty much followed the sample code, but I keep getting the message "Cancelled: Transaction not allowed". There is not much information for me to go on to try and fix this. What am I doing wrong?

 

Aside... where do I get the SDK for DotNet? GitHub? If so which dll, there are a few there.