RESTCONF Operations (RPC) Toaster invocation not working ?

I am attempting to understand the ODP RESTCONF interface and using the toaster sample to experiment. Based on the YANG file and the readings I can find, it looks like the following URL should invoke a "make-toast" operation:

http://admin:admin@<host>:<port>/restconf/operations/toast:make-toast

This URL gives and exception, I also tried "toaster:make-toast", but this also gives an exception.

I am not entirely sure if this is an bug or pilot error, but just to have it checked out, I am submitting it as an error.