Releasing Smoke from Aircraft

Well, I'm relatively new to FSX, as I got it this Christmas, and there is something that I would really like to know.

How can I add and use smoke on any aircraft, downloaded or default aircraft.

I've had planes that had a [SMOKE SYSTEM] section in their .cfg files, yet, when I get in them and use them in flight, and hit the smoke hotkey, it doesn't release smoke.

I've looked around for tutorials on how to add the smoke, but none of them have helped. I tried adding a hotkey on my joystick to see if it was just something wrong with my keyboard or something of the sort. It didn't work.

So if anyone could tell me how to add smoke (if it is possible) to an aircraft, and then use it in flight, it would be greatly appreciated.

Thanks in advance for any and all help!