Mission Planner with MavLink

How can i see the Mavlink messages send and receive by Mission Planner ?
I found Mavlink inspector but i don’t understand it. I have a joystick linked to MP but when i configure everything and i move the joystick, the mavlink inspector doesn’t change. I dont understand.

Thank you for your help.

Do you have your joystick inputs mapped to RC channels?
It should look like this:

Or when you graph it: