Waypoint Perform Command with Script File not work

[Tanuki44]

In a waypoint action,
Whatever the code, it works perfectly in a perform command with a copied and pasted script.
But if the same code is in a *.lua file, the perform command with script file doesn't work...
Tried with this code example :
trigger.action.outText('aircraft has reached WP', 3)
Thanks for any help