If you are getting nothing it suggests a wiring problem.
It would be useful to know which connections you have made between the Pi and the MCP23S17 and details of what is connected to the MCP23S17 gpios.
That monitor (possibly my software) should be capable of monitoring the gpios if properly configured.
For a more visual and possibly simpler approach I suggest you download my pigpio library and piscope which is how I tend to debug these sorts of problems.
To use piscope you'll have to temporarily drop the SPI speed to something like 50000 bps but that shouldn't affect your program logic.