llList2Float car gearing?

im having alot of crazy trouble in theory this should work, im using a list to create a gearing system for my car. it works good except it dosent stop at the last set of gears but it will stop at first gear anyone have any ideas?

gears will go 1-2-3-4-5-6-7 and so on then 7-6-5-4-3-2-1 will stop at first gear

list ForwardPowerGears = [12, 13, 16, 20, 30];
integer Gear = 0;
integer NumGears;
float ForwardPower;

//------------------------------------------------------\\

if((edge & level & CONTROL_UP))
        {
            if((Gear + 1) != NumGears)
            {
                ++Gear;
                llWhisper(0, "Gear " + (string)(Gear + 1));
                ForwardPower = llList2Float(ForwardPowerGears, Gear);
            }
        }
        else if((edge & level & CONTROL_DOWN))
        {
            if((Gear - 1) != -1)
            {
                --Gear;
                llWhisper(0, "Gear " + (string)(Gear + 1));
                ForwardPower = llList2Float(ForwardPowerGears, Gear);
            }
        } 
        if(level & CONTROL_FWD)
        {
            llSetVehicleVectorParam(VEHICLE_LINEAR_MOTOR_DIRECTION, <ForwardPower,0,0> );
        }

Setting a value for NumGears may help

OMFG it worked