When you buy a tool it gives you negative leaderstats?

So when you click a button then you get a tool in your backpack only if you have 15 levels in the leaderstats and it takes away 15 levels from you but instead it takes away like a lot of levels and it gives you a negative value here is my script:

script.Parent.ClickDetector.MouseClick:Connect(function(player) local playerLevel = player.leaderstats.Level playerLevel.Value = playerLevel.Value + 1

if playerLevel.Value >= 15 then
    local ReplicatedStorage = game:GetService("ReplicatedStorage")
    local ToolGiver = game.Workspace.ToolGiver
    local PartTool = game.ReplicatedStorage.PartTool
    ToolGiver.ClickDetector.MouseClick:Connect(function()
        PartTool:Clone()
        PartTool.Parent = player.Backpack
        playerLevel.Value = playerLevel.Value - 15
    end)
end

end)