Mouse1OnClick doesn't work for me when I clicked on the button. I did very simply, but it did not work. My script was stored in, StarterGUI --> ScreenGUI ---> Frame --> Button --> Script. The print did not output in the Output Page.
script.Parent.MouseButton1Click(function()
print("Test")
end)

1 comment
Other than Prismatic's answer - if you are having trouble understanding usage or have questions about why you need to use Connect -- it is much more visible in named functions rather than anonymous ones. https://hastebin.com/nodifenavo.sql