onButton1Down won't fire in tool?

I'm trying to make a (relatively) simple fully-automatic gun. I won't post the entire code, but this is where something's going wrong:

function onEquipped(mouse)
    print("Check 1") --This works
    mouse.Button1Down:connect(function() onButton1Down(mouse) end)
end

gun.Equipped:connect(onEquipped)

...And above that I have the onButton1Down function...

function onButton1Down(mouse)
    print("Check 2") --This doesn't work
    --...more code
end