Alternative fire in bad company 2

This has bothered me for a while now... please forgive the noob question

How do I fire the alternative fire in vehicles? Or the Countermeasures for the heli that aperantly was in the last patch but I've yet to see. Now my right mouse button is supposed to be the alt-fire according to the settings but it doesnt seem to work. What can I be missing?

I've never been able to fire that second rocket as the pilot or the tracer dart as the gunner of the apache. I've only once figured out the secondary fire for the drone and the tank but havent been able to repeat either recently. I'm missing something fundimental here...

You need to equip this part of your class's vehicle specialization:

Alternate Weapon Package

A weapons package that upgrades the targeting systems of vehicles and helicopters. It extends the effective range and accuracy of mounted weapons. - Adds an alternate weapons to the vehicle. Such as the M1A1, will have a secondary machine gun that you can control along with your main gun.

Its a vehicle specialization and requires 10,000 vehicle experience points to unlock.

More details here.