Help with 3rd selectable firearm?

Hi!
I'm working on the zoom for our tanks in "Operation Peacekeeper", but i've still a CTD with it.

Before, the tanks had two selectable weapon systems: HEAT and SABOT
the third weapon, coaxial mg was on the right mouse button
the smokelauncher was still on PIFlarefire

now i want to select the three weapons with mousewheel:
SABOT, HEAT and the coaxial mg

right mouse button for the zoom

and PIFlarefire for the smokelauncher

i tried to do this, but if i try to select down to coaxial mg, the game CTD without error message. i tried it in window mode, but there is even no error message.
HEAT and SABOT can be select and fired, but if i scroll down to mg, it crashes.:shock:

what is wrong? can u help me?

here are the vehicle.con and the vehicle.tweak :

the *.con file
the *.tweak file:
thx, DaWallace