XP Leaderboard auto-stat change script not working?! Help!?

Hello everyone, I'm making a script that will change the players leader board rank when they reach a certain amount of XP, I was recently helped out by berezaa, but I've got stuck again

Here is my script I've been using:

(its not a local script btw)

function onPlayerEntered(newPlayer)
local user = game.Players:findFirstChild(newPlayer)
local stats = user:findFirstChild("leaderstats")
while true do
		if stats ~= nil then 
			local rank = stats:findFirstChild("Rank")
			local xp = stats:findFirstChild("XP")
if xp >= 75000 then
    rank = "Commanding Officer"
elseif xp >= 65000 then
    rank = "General"
elseif xp >= 50000 then
	rank = "Admarial"
elseif xp >= 45000 then
	rank = "Cononel"
elseif xp >= 35000 then
	rank = "Captian"
elseif xp >= 37500 then
	rank = "First LT"
elseif xp >= 36500 then
	rank = "Second LT"
elseif xp >= 30000 then
	rank = "Master Sergeant"
elseif xp >= 25000 then
	rank = "Sergeant"
elseif xp >= 23500 then
	rank = "Warrant Officer 1"
elseif xp >= 21550 then
	rank = "Warrant Officer 2"
elseif xp >= 20000 then
	rank = "Corparol"
elseif xp >= 7500 then
	rank = "Private First Class"
elseif xp >= 250 then
	rank = "Private"
elseif xp >= 550000 then
	rank = "Moderator"
elseif xp >= 750000 then
	rank = "Administrator"
elseif xp >= 1500000 then
	rank = "Head Administrator"
elseif xp >= 3500000 then
	rank = "Peace Keeper"
elseif xp >= 5500000 then
	rank = "The Victorious"
elseif xp >= 0 then
	print("M8 he just getting started!")
end 
end
end
end

game.Players.ChildAdded:connect(onPlayerEntered)
		

If you could help I'd really appreciate it!

There was also an error code:

Workspace.RA.Script:3: attempt to index local 'user' (a nil value)

The problems are on the lines where you check the xp and rank. You're checking if the object itself equals a number, which will be false. You should add a .Value for each time you want to check the value/change it.

local function onPlayerEntered(newPlayer) -- Globals are bad practice. Use locals!
    local stats = newPlayer:FindFirstChild("leaderstats") -- findFirstChild deprecated 

    if stats then 
        local rank = stats.Rank
        local xp = stats.XP

        if xp.Value >= 75000 then-- Check value!
            rank.Value = "Commanding Officer"--changing value
        elseif xp.Value >= 65000 then
            rank.Value = "General"
            print("M8 he just getting started!")
        end
    end
end

game.Players.PlayerAdded:Connect(onPlayerEntered) -- connect is deprecated! and use PlayerAdded

On your own you will add the .Value.

Now your indentation. Your code is very messy. It is important to indent your code for the sake of readability. Though indentation does not affect the output of your code, it is important to have it indented. In other programming languages such as Python (not sure if there's other languages), it is indentation-sensitive. There is no end keyword that signifies the end of a function, for, while or if like in Lua.

Finally, do not use ChildAdded to listen for a player joining, as ChildAdded fires for any object added, including non-Player objects, and it is possible to parent non-Player objects to Players, which can cause problems with poorly written code.