[1.8] Reading data from a vanilla furnace

Hello everyone,

I got a GUI in which I need to read data from a furnace. So I am delivering the ISidedInventory of the furnace via a container.

My Problem right now is that for some reason ISidedInventory.getField(2) is ALWAYS returning 0, even if it should be the cook time of the current item..

Of course I placed coal and iron ore in the furnace to make it burn

public class FurnacesGui extends GuiContainer{

private final ResourceLocation background = new ResourceLocation("advancedfurnaces:textures/gui/allfurnaces.png");

private int furnaceSlots;
private ISidedInventory[] furnaces;

public FurnacesGui(ContainerAllFurnaces container) {
	super(container);
	furnaceSlots = container.getAllFurnaceSlots();
	furnaces=container.getFurnaces();


}

@Override
protected void drawGuiContainerBackgroundLayer(float partialTicks,
		int mouseX, int mouseY) {
	GlStateManager.color(1.0F, 1.0F, 1.0F, 1.0F);
	mc.renderEngine.bindTexture(background);
	int k = (this.width - this.xSize) /2 ;
	int l = (this.height - this.xSize) /2 ;
	drawTexturedModalRect(k, l, 0, 0, xSize, ySize);

	int pixelToDraw;
	for(int i=0; i<furnaceSlots; i++)
	{

		pixelToDraw= 22*furnaces[i].getField(2)/furnaces[i].getField(3);
		System.out.println(furnaces[i].getField(2));
		System.out.println(furnaces[i]);

		drawTexturedModalRect(k+10+20*i, l+10, 206, 0, 16, 60);
		drawTexturedModalRect(k+11+20*i, l+29, 224, 0, 16, pixelToDraw);

	}
}

}