Not being able to call function(s)?

I've never really understood the way function calling works. In some of my games, trying to call mutiple function will cause the game to only call one specific function. What's with that!

And I've ran into this problem yet again. There are no errors in the output, but when I try to call the two functions at lines 58 - 62, only "DisplayPI()" works. If all the lines of code over welms you ;), only focus on the lines where a function is called. THX!!!

function DisplayPI(back,Primary)
    wait()
    print("PI")
    local x = 0
    local y = 0
    local var = 0
    while player ~= nil do
        wait()
        var = var + 1
        x = x + 1
        y = x
        back["Column" .. Index].Text = back["Column" .. Index].Text .. string.sub(Primary,x,y)
        if var >= 65 then
            var = 0
            Index = Index + 1
            print(Index)
            if Index == 8 then
                print("J")
            end
        end
    end
end

function ScrollColumns(back)
    print("HELLO")
    repeat wait() until Index >= 8
    local var = 0
    while player ~= nil do
        repeat wait() until var >= 60 or var == 0
        for i=1,60 do
            wait(1/30)
            var = var + 1
            for i,v in pairs(back:GetChildren()) do
                v.Position = v.Position + UDim2.new(0,0,-.001,0)
                if v.Position.Y.Scale <= -.1 then
                    v:Destroy()
                end
            end
        end
    end
end

function LoadColumns(back)
    print("PI")
    local var = -.1
    for i=1,10 do
        var = var + .1
        Instance.new("TextLabel",back).Size = UDim2.new(1, 0, 0.1, 0)
        back.TextLabel.Position = UDim2.new(0, 0 ,var ,0)
        back.TextLabel.BackgroundTransparency = 1
        back.TextLabel.FontSize = Enum.FontSize.Size18
        back.TextLabel.Text = ""
        back.TextLabel.TextXAlignment = Enum.TextXAlignment.Left
        back.TextLabel.Name = "Column" .. (tostring(var*10))
    end
    repeat wait() until var >= .8
    print("j")
    DisplayPI(back,player.Backpack.Primary.Value)
    print("jl")
    ScrollColumns(back)
    print('jks')
end