'addrecipe' crashing the game when loading custom mod please help

[BRADLEYBONES007]

sorry for being inconvenience

my mod keeps crashing after I've tried to add a custom tab and a recipe for an item included in it

unk_tab = AddRecipeTab(STRINGS.NAMES.UNK_TAB, 5, "images/hud/Unknown.xml", "Unknown.tex", nil, false)

local skullhelm = AddRecipe("skullhelm", {Ingredient("carrot", 2), Ingredient("twigs", 1)}, unk_tab, TECH.NONE , nil , nil, nil, nil, "unknown")

these two lines seem to be the problem as the log.txt says :

attempt to call global 'AddRecipeTab' (a nil value)

I'd like some help with this please

thanks for your time

Unknown mod.zip

log.txt