getting this on compile:

Failed to call hook 'OnServerInitialized' on plugin 'ZoneManager v3.0.15' (ArgumentException: An item with the same key has already been added. Key: 2020)
  at System.Collections.Generic.Dictionary`2[TKey,TValue].TryInsert (TKey key, TValue value, System.Collections.Generic.InsertionBehavior behavior) [0x000c1] in <437ba245d8404784b9fbab9b439ac908>:0 
  at System.Collections.Generic.Dictionary`2[TKey,TValue].Add (TKey key, TValue value) [0x00000] in <437ba245d8404784b9fbab9b439ac908>:0 
  at Oxide.Plugins.Hash`2[TKey,TValue].Add (TKey key, TValue value) [0x00000] in <d09a1f46ca2f4432811bcfe45ad13c7b>:0 
  at Oxide.Plugins.ZoneManager.CreateZone (Oxide.Plugins.ZoneManager+Zone+Definition definition) [0x0001e] in <9b49fa16de024e5f8aa35ca92987d824>:0 
  at Oxide.Plugins.ZoneManager.InitializeZones () [0x0002a] in <9b49fa16de024e5f8aa35ca92987d824>:0 
  at Oxide.Plugins.ZoneManager.OnServerInitialized () [0x00000] in <9b49fa16de024e5f8aa35ca92987d824>:0 
  at Oxide.Plugins.ZoneManager.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x001ad] in <9b49fa16de024e5f8aa35ca92987d824>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <d09a1f46ca2f4432811bcfe45ad13c7b>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <cf88a28c7fb44d36890d85a78331cc9d>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <cf88a28c7fb44d36890d85a78331cc9d>:0 
Loaded plugin Zone Manager v3.0.15 by k1lly0u​

and this when I do /zonemanager:

Failed to call hook 'OnPlayerConnected' on plugin 'ZoneManager v3.0.15' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.ZoneManager.OnPlayerConnected (BasePlayer player) [0x00000] in <3e168ca9d4cc425784ef4699a350b4b0>:0 
  at Oxide.Plugins.ZoneManager.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00395] in <3e168ca9d4cc425784ef4699a350b4b0>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <d09a1f46ca2f4432811bcfe45ad13c7b>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <cf88a28c7fb44d36890d85a78331cc9d>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <cf88a28c7fb44d36890d85a78331cc9d>:0 ​

I'm sure you can fix it, thanks beforehand.