UserInputService problem when "inputting" a mouse button, any fix/alternative?

So my problem is this: When a mouse button is pressed and recorded by way of "UserInputService", it's KeyCode is returns as "Enum.KeyCode.Unknown".

Now, it returning that whenever, say, right mouse button is clicked is fine, the problem is that it returns that for any/all mouse buttons!

So, is there a way to properly return the KeyCode for mouse buttons with "UserInputService"? If not, what's the best alternative way to get the mouse button clicked? (preferably in Enum.KeyCode format)

Here's some code:

--Made in Local script in StarterGui.
local Input_Service =game:GetService("UserInputService")

Input_Service.InputBegan:Connect(function(input)
	print(input.KeyCode)--When you press any mouse button, you get "Unknown".
end)

I hope this helps,

Thanks.