its printing nil and i cant figure out why?

its printing nil and idk why it is, ive double checked everything and i cant find anything that would go wrong?!

local thing = {"Standard Crate", "Specialized Crate", "Rare Crate", "High-End Crate", "Exotic Crate", "God-Tier Crate"}

local function checkcrate(crate)
    local a = nil
    local check = crate.CrateClaim.CrateGuiNotification.ObjectImage.CrateName.Value
    for i, v in pairs(thing) do
        if check == v then
            a = v
        end
    end
    return(a)
end
for i, v in pairs(game.workspace:GetDescendants()) do
    if v.Name == "Crate" and v:FindFirstChild("Smoke") ~= nil then
        local j = checkcrate(v)
        print(j)
    end
end