I have figured out what I was doing wrong with registering wideclient. I assumed that the registration process had to take place on the client computer itself, not on the server computer. Of course the FSUIPC software is registered on the server computer and I understood that the fsuipc installation process includes an opportunity to register FSUIPC, wideclient, or both, but I did not suspect that we do the wideclient registration (for the client computer) on the server computer itself.
Upon rereading the installation instructions, I see that registering of WideFS7 takes place under the "On the Flight Simulator PC" section of the instructions. Nonetheless, it is so strange to me to register the software for one computer on another computer that I didn't make the connection that the event took place on the server computer.