Code is located in a localscript / local ItemButton = script.Parent.ItemsButton
ItemButton.MouseButton1Click:connect(function() print "worked" end) / If I could also get be told how to resolve this I'd appreciate it.
If the script is inside of the button then just use script.Parent instead of script.Parent.ItemsButton. Also check for any spelling mistakes.
local ItemButton = script.Parent ItemButton.MouseButton1Click:Connect(function(check) print("It worked!") end)
Try putting this script inside the button.