Here's an example on how to create a working radio trigger. Look up each of the commands used in the comref to see what possible settings you can have:
_trig = createTrigger ["EmptyDetector", (getpos Player)]
_trig setTriggerArea [0, 0, 0, false]
_trig setTriggerActivation ["ALPHA", "PRESENT", true]
_trig setTriggerStatements ["this", "hint ""Trigger activated""", ""];
1 setRadioMsg "Alpha Radio"
This will create a repeating radio Alpha (0-0-1) radio trigger that will hint "Trigger activated" whenever used. Its radio message will be "Alpha Radio". I believe the above are the minimum statements you need to create a properly working trigger.
Note: if you want to delete the trigger, you need to use
deleteVehicle _trig: so if you want to access it in other scripts you might want to give it a global, not a _local name. Also, making the trigger invisible for the moment is easily done by writing
1 setRadioMsg "NULL". 1 = radio Alpha. You can have an endless amount of triggers activated by Radio Alpha, all doing different things, and wether they activate or not can be dependent on the conditions you set in the triggerStatements command.
Good luck!
Wolfrug out.