How to activate Mission_Start > Do Action

Dear all,

It’s about starting a mission in MP1.3.39 by using my laptop only.(so without Radio Control- unit)

As I’m trying to start a mission in the Actions-tab by ‘Do Action’ in Mission_Start after Arming, nothing will happen, My Quad just disarms after a couple of seconds. Only… when I use my RC- unit (DX8) with a small Throttle offset I can start as an Auto mode.
My question is: how can I start a pre-saved Waypoint- file Without interacting my RC- unit?
(So as a fully autonomous mission) I just prefer to have my RC-unit standby for emergency cases.

I hope I succeeded in makking clear my ‘problem’

thank you so much for your prompt reply.