Accessing Backpack from Server?

I'm trying to access a value inside the Players Backpack via a script from the server:

function onClick(plr)
    local find = game.Players.LocalPlayer.Backpack.Player_Inv:FindFirstChild("Lock Pick")
    if find ~= nil then
        if find.Amount.Value > 0 then
            script.Parent:Destroy()
            find.Amount.Value = find.Amount.Value - 1
        end
    end
end

script.Parent.ClickDetector.MouseClick:connect(onClick)

Scripts like these have worked in the past, so I'm not sure what the problem is here. Also, there is nothing printed in the output related to this script. Help?