Eigene Funktion aufrufen

Hallo,

ich bin bei dem Versuch mein eigenes Skript MP Ready zu machen schon am auslagern des Codes in einzelne Funktionen gescheitert.

[lua]
Twinwheels = {};

function Twinwheels.prerequisitesPresent(specializations)
return SpecializationUtil.hasSpecialization(Motorized, specializations);
end;

function Twinwheels:load(xmlFile)
self.leftFrontTwinwheel = Utils.indexToObject(self.components, getXMLString(xmlFile, "vehicle.Twinwheels.leftFrontwheel#index"));
self.rightFrontTwinwheel = Utils.indexToObject(self.components, getXMLString(xmlFile, "vehicle.Twinwheels.rightFrontwheel#index"));
self.leftBackTwinwheel = Utils.indexToObject(self.components, getXMLString(xmlFile, "vehicle.Twinwheels.leftBackwheel#index"));
self.rightBackTwinwheel = Utils.indexToObject(self.components, getXMLString(xmlFile, "vehicle.Twinwheels.rightBackwheel#index"));

self.allTwinwheelsactive = false;
end;

function Twinwheels:delete()

end;

function Twinwheels:mouseEvent(posX, posY, isDown, isUp, button)
end;

function Twinwheels:keyEvent(unicode, sym, modifier, isDown)
end;

function Twinwheels:reifenwechsel(noEventSend)
self.allTwinwheelsactive = not self.allTwinwheelsactive;
print("Funktion Reifenwechsel angesprochen");
if not noEventSend then
TwinwheelsEvent.sendEvent(self, self.allTwinwheelsactive, noEventSend);
end;
setVisibility(self.leftFrontTwinwheel, self.allTwinwheelsactive);
setVisibility(self.rightFrontTwinwheel, self.allTwinwheelsactive);
setVisibility(self.leftBackTwinwheel, self.allTwinwheelsactive);
setVisibility(self.rightBackTwinwheel, self.allTwinwheelsactive);
end;

function Twinwheels:update(dt)
if self:getIsActiveForInput() then
if InputBinding.hasEvent(InputBinding.ALLTWINWHEELS) then
--self.allTwinwheelsactive = not self.allTwinwheelsactive;
self:reifenwechsel(self.allTwinwheelsactive);
end;
end;

end;

function Twinwheels:draw()
g_currentMission:addHelpButtonText(g_i18n:getText("Twinwheels"), InputBinding.ALLTWINWHEELS);
end;[/lua]
In der log steht :

Lua: Error running function: update
C:/Users/rafftnix/Documents/My Games/FarmingSimulator2011/mods/FendtPackage/Twinwheels.lua(44) : attempt to call method 'reifenwechsel' (a nil value)