Servers by jDrones

Pixhawk connect MP by 4G telemetry "No Heartbeat Packets Received"

Hello
I wanna make a 4G telemetry(raspberry pi & 4G dongle)
and follow the step of this video:


However, I got the message “No Heartbeat Packets Received”
I don’t know what the problem is
Can anyone help?
THX!!!

following videos are how I connect and RPI can successfully connect to pixhawk

no heartbeat packets received

raspberry pi to pixhawk

Servers by jDrones