Trouble with extended parameter protocol

[Ryan]

Hello, I'm having some trouble understand the flow of data with the extended camera protocol.  I'd like to be able to change some setting defined in an external XML such as ISO, Aperture, shutter speed etc.  I have the xml created and the sample camera_server running as I'd like.  The server sends out the uri and it is downloaded and the parameters are created in QGC.  However when they send back to the camera server I get the following. 

[03:36:46|Warn ] Ignoring request_read message extended - param name not found: CAM_SHUTTERSPD (mavlink_parameter_server.cpp:370)
[03:36:46|Debug] process param_ext_request_read (mavlink_parameter_server.cpp:335)
[03:36:46|Warn ] Ignoring request_read message extended - param name not found: CAM_ISO (mavlink_parameter_server.cpp:370)
[03:36:46|Debug] process param_ext_request_read (mavlink_parameter_server.cpp:335)
[03:36:46|Warn ] Ignoring request_read message extended - param name not found: CAM_EXPMODE (mavlink_parameter_server.cpp:370)
[03:36:46|Debug] process param_ext_request_read (mavlink_parameter_server.cpp:335)

I was under the impression that the extended parameter protocol allowed the use of such settings without creating a whole new plugin, is that correct?  And if so how do I set the parameters in the parameter server and then how do I subscribe to the changes?  

Any help or even a single changed extended parameter version of the camera server example would be a huge help in getting me moving again.  

[Ryan]

This is all being written in C++ with the MAVSDK library on Linux.