why is this leaderstats script unreliable?

sometimes the deaths leaderboard appears and sometimes it isnt there, why does this happen?

local dss = game:GetService("DataStoreService")

local deathsDataStore = dss:GetDataStore("deathsDataStore")

game.Players.PlayerAdded:Connect(function(player)

    local leaderstats = player:WaitForChild("leaderstats")

    local deaths = Instance.new("IntValue")
    deaths.Name = "Deaths"
    deaths.Parent = leaderstats

    local data
    local success, errormsg = pcall(function()
        data = deathsDataStore:GetAsync(player.UserId.."-deaths")
    end)

    if data == nil then
          data = 0
    end

    if data ~= nil then
        deaths.Value = data
        print(player.Name.."'s deaths data was retrieved!")
    else
        print("Error while getting "..player.Name.."'s deaths data.")
        warn(errormsg)
    end

end)

game.Players.PlayerRemoving:Connect(function(player)

    local success, errormsg = pcall(function()
        deathsDataStore:SetAsync(player.UserId.."-deaths",player.leaderstats.Deaths.Value)
    end)

    if success then
        print(player.Name.."'s deaths data was saved!")
    else
        print("Error when saving "..player.Name.."'s deaths data.")
        warn(errormsg)
    end

end)