try it with my example i use for my game

ACTION Metal_Opties
{
my.invisible = on; // so it is hidden
my.ENABLE_SONAR = on; //activate sonar
my.event = pickup_event; //event call
}

function pickup_event()
{


if (event_type == EVENT_SONAR) // if you get in the sonar
{

beep;
beep;
beep;

}
}


Try this maybe it is what you want.