Why is it saying attempt to index nil with Backpack?

So I have this normal script:

script.Parent.Triggered:Connect(function(player)
    local tool = script.Parent.Parent.Parent.Parent.BoxTool:Clone()
    local path = game.Players:FindFirstChild(player)
    tool.Parent = path.Backpack
    print(player)
end)

This script prints the player correctly. the path variable is fine. But whenever I try to access Backpack, it says attempt to index nil with Backpack. I tried this with FindFirstChild() and WaitForChild(), but it would say attempt to index nil with FindFirstChild() or WaitForChild depending on what I wrote.