Graupner HOTT is not working on kakute f7 AIO

Hi everyone,I just get kakute f7 AIO and load the firmhware copter 4.0.7,and I want to use HOTT at serial4, I follow the setting on ardupilot wiki page ,but the MZ-12 pro is not showing any data on screen(restart the remote and copter is not working),but last time this remote and reciver was working well on kakute f4 AIO (copter 4.0.7)and pixhawk 2.4.8 (copter 4.0.7)with same setting.
Then I try to fall back to copter 4.0.6 on kakute f7 AIO , it’s seems not working too.Therefore I use the oscilloscope to see the waveform at pixhawk 2.4.8 serial4 TX pin and compare with the serial pin at kakute f7 aio, and the reciver sends the signal but the kakute is not responding,with the same serial setting on serial1/serial2/serial3/serial4 get the same result,I also try the serial1/2/3/4 was worked with mavlink,I don’t know what the problem is,sorry for my poor english