Setting CIRCLE_RADIUS via SET_PARAMETER command not working

I’d like to send MAV_CMD_DO_SET_PARAMETER command via MAVLink to set the value of CIRCLE_RADIUS parameter. I think I found the numeric value of this parameter here but when I tried to set parameter number 215 to be 30 but MAVProxy’s console displayed

Got MAVLink msg: COMMAND_ACK {command : 180, result : 3}

Could someone please tell me what is the right way to set a parameter via MAVLink?