It appears that Its not giving kills when you kill someone with a AK-47, why?

So I made a tool with a GUI Inside It which Is used to keep on track on how many kills you currently have, to get kills you must kill someone with a AK-47, Currently there is a problem where It won't give me kills even If you kill someone with the AK-47, there Is a error that says:

TextLabel Is not a valid member of ScreenGUI "Players.imnotaguest1121 (Thats my username).PlayerGUI.ScreenGUI

Local script (Shows GUI and bugged/glitch give kills):

wait(1)
GUI = script.Parent.ScreenGui
local Player = game.Players.LocalPlayer
local Kills = 1

script.Parent.Equipped:Connect(function()
    local GUIClone = GUI:Clone()
    GUIClone.Parent = Player.PlayerGui
    script.Parent.Unequipped:Connect(function()
        GUIClone:Destroy()
    end)
    script.Parent.GiveKill.OnClientEvent:Connect(function() ---Used a RemoteEvent
        Kills = Kills + 1
        GUIClone.TextLabel = "Kills: "..Kills
    end)
end)

And If you want, the server script: (Look at Line 22):

local tool = script.Parent
local Shoot = tool.Shooting
local PewAnimation = tool.Animation

tool.Fire.OnServerEvent:Connect(function(player,mousePos)
    local Humanoid = tool.Parent.Humanoid

    local AnimationTrack = Humanoid:LoadAnimation(PewAnimation)
    AnimationTrack:Play()
    Shoot:Play()
    local raycastParams = RaycastParams:new()
    raycastParams.FilterDescendantsInstances = {player.Character}
    raycastParams.FilterType = Enum.RaycastFilterType.Blacklist

    local raycastResault = workspace:Raycast(tool.Handle.Position,(mousePos - tool.Handle.Position)*1000,raycastParams)
    if raycastResault then
        local hitpart = raycastResault.Instance
        local model = hitpart:FindFirstAncestorOfClass("Model")
        if model then
            if model:FindFirstChild("Humanoid") then
                model.Humanoid.Health -= math.random(1,2)
                if model.Humanoid.Health <= 1 then
                    tool.GiveKill:FireClient(player)
                end
            end
        end
    end
end)