How come my playerMounted never is called?

In player.cs if I put an echo() in the function

function Armor::onMount(%this,%obj,%vehicle,%node)

I can get things working fine, but if I want specific vehicle (Vamp for this example) to do things I thought I am suppost to use the function

function Vamp::playerMounted(%data, %obj, %player, %node)

and nothing gets called. This is a modified vehicle.cs from Tribes 2. What would be the correct function name?