Sending rc_channels_override to px4

Hello all,
I am trying to use rc_channel_override. I am using python with mavutil.
This is my code to send my message:
master.mav.rc_channels_override_send(0, 0, 2000, 1500, 1500, 1500, 1500, 1500, 1500, 1500)
print(“Sent Message”)

where master is (the_connection) show in documentation. I have the plane flying HIL with xplane 10 in stab. I also tried manual but I got no response when I send this message. I see rc_channel_overide is in the PX4 mavlink_receiver.cpp file so I think this should be working.

any ideas?