Sending manual control to FC from an Arduino

I’m trying to send mavlink_msg_manual_control_pack to Flight controller from Arduino connected to the flight controller on the Rx/Tx Serial.

I was able to send the FC if set the msg from sysid 255 comp id190. I can hear the connection beep but I can hear the unhappy tone and it seem to disconnect I think. I try sending 1 Hz heartbeat but no luck. Every time I send manual control msg, it would connect and send the msg but disconnect.

I just want to be able to control the FC with manual control from my Arduino
I’m not sure what am I doing wrong. Any help would be appreciated

Thank you