GroupRank Leaderboard doesn't work?

Hello

I try to create a group rank leaderboard but it isn't working. Can someone help? What I do wrong?

local GroupID = 3555315 --This is the group ID Number

   game.Players.PlayerAdded:connect(function(player)
    local stats = Instance.new("IntValue", player)
    stats.Name = "Leaderstats"

    local RankDisplay = Instance.new("StringValue", stats)
    RankDisplay.Name = "Ranks" --Leaderboard stat name
    RankDisplay.Value = player:GetRoleInGroup(GroupID)

end)

Thanks for help!