Keep getting a "attempt to call a nil value" in my output?

I keep getting an "attempt to call a nil value" in my output every time I click on a button, here's my scripts.

local clickDetector = script.Parent.ClickDetector

if script.Parent.Parent.Name == ("Can I get a burrito?") then
    function onMouseClick()
        script.Parent.Parent.Name = ("Thank you!")
    end
end

clickDetector.MouseClick:connect(onMouseClick)

Note that the first script is the same for every name text

while true do
    creativlyNamedVariable = math.random (1, 4)
    if creativlyNamedVariable == 1 then
        script.Parent.Name = ("Can I get a taco?")
    elseif creativlyNamedVariable == 2 then
        script.Parent.Name = ("Can I get some nachos?")
    elseif creativlyNamedVariable == 3 then
        script.Parent.Name = ("Can I get a burrito?")
    elseif creativlyNamedVariable == 4 then
        script.Parent.Name = ("Can I get a soda?")
        if script.Parent.Name == ("Thank you!") then
            wait(30.8)
            creativlyNamedBye = math.random (1, 3)
            if creativlyNamedBye == 1 then
                script.Parent.Name = ("Bye!")
            elseif creativlyNamedBye == 2 then
                script.Parent.Name = ("Cya!")
            elseif creativlyNamedBye == 3 then
                script.Parent.Name =("Alright, have a good one!")
            end
        end
    end
    wait(35.8)
end 

EDIT: So I just tested it again. But it works with some buttons one time, and then others when I test it another time.