How come i get the error "attempt to concatenate string with Instance"??

So, For some reason. Everytime the "CurrentlyInfecting" Value changes, It gives the output: "attempt to concatenate string with Instance" and im so confused, Help??

local leaderstats = script.Parent.Parent.Parent.Parent.leaderstats
script.Parent.Parent.Parent.Parent.leaderstats.CurrentlyInfecting.Changed:Connect(function()
	script.Parent.Text = "Infected: ".. leaderstats.CurrentlyInfecting .."/"..leaderstats.MaxInfect
		print("Works")
end)

The error is pretty self-explanatory, your trying to concatenate a string with an instance. You cant do that because the instance it self is not a string (or number) so you will have to use some properties of the instance:

If its a value do as DeUltimate23 said, put a .Value on the end. If its a part or something like that put .Name on the end.