Timed out waiting for system

[Steven-Ajex]

I'm using MAVSDK to run some test,here is how i do it:
1.I connected the PC with my flight controller through serial
2.I run : build/takeoff_and_land serial:///dev/ttyUSB0:9216

most of the time it will print
[05:05:55|Info ] MAVSDK version: v2.12.2-136-ga81d2588-dirty (mavsdk_impl.cpp:28) Timed out waiting for system
but it will always work if i rerun it again
[05:05:55|Info ] MAVSDK version: v2.12.2-136-ga81d2588-dirty (mavsdk_impl.cpp:28)
[05:05:55|Debug] New system ID: 1 Comp ID: 1 (mavsdk_impl.cpp:743)
[05:05:55|Debug] Component Autopilot (1) added. (system_impl.cpp:377)
[05:05:55|Warn ] Vehicle type changed (new type: 2, old type: 0) (system_impl.cpp:217)
[05:05:55|Debug] Discovered 1 component(s) (system_impl.cpp:497)
[05:05:55|Debug] Request message 148 using REQUEST_MESSAGE (mavlink_request_message.cpp:78)

"Does anyone know how to solve this?Thanks a lot"

[julianoes]

9216 doesn't look like a real baudrate?