private class PVEStatsData
        {
            public int heavyKills = 0;
            public int scientistkills = 0;
            public int murdererkills = 0;
            public int scarecrowkills = 0;
            public int points = 0;
            public string rank;
            internal static void TryLoad(ulong id)
            {
                if (Cachedplayerstats.ContainsKey(id)) return;

                PVEStatsData data = Interface.Oxide.DataFileSystem.ReadObject<PVEStatsData>($"NPCKillCounter/{id}");

                if (data == null) data = new PVEStatsData();

                Cachedplayerstats.Add(id, data);
            }
            internal static void Reset(ulong id)
            {
                PVEStatsData data = Interface.Oxide.DataFileSystem.ReadObject<PVEStatsData>($"NPCKillCounter/{id}");

                if (data == null) return;

                data = new PVEStatsData();
                data.Save(id);
                                           
            }
            internal static void resetcache(ulong id)
            {
                if (!Cachedplayerstats.ContainsKey(id)) PVEStatsData.TryLoad(id);
                Cachedplayerstats[id].heavyKills = 0;
                Cachedplayerstats[id].scarecrowkills = 0;
                Cachedplayerstats[id].scientistkills = 0;
                Cachedplayerstats[id].murdererkills = 0;
                Cachedplayerstats[id].points = 0;
            }
           
           
            internal void Save(ulong id) => Interface.Oxide.DataFileSystem.WriteObject(($"NPCKillCounter/{id}"), this, true);
        }

if (Cachedplayerstats[player.userID].points == rank1)
            {
                player.IPlayer.AddToGroup((string)Config["Rank1"]);
                Cachedplayerstats[player.userID].rank = (string)Config["Rank1"];
            }

I have this and its supposed to set the players rank in the data file to the one in the config, when a player reaches a certain amount of points. I have done something wrong as in the data file, the value for rank will only show up as null. I am not sure what i have done wrong, can someone help me plz?