NullReferenceException at UpdateRaidLimitUIError

Hi, I have this errror

21:24 [Error] Failed to call hook 'OnEntityTakeDamage' on plugin 'RaidLimit v2.1.1' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.RaidLimit.UpdateRaidLimitUI (BasePlayer player, System.Boolean Imageupdate, System.Int32 FontSize, System.String Msg) [0x00000] in <9241bd57b11c46f7b737959bb704a1f2>:0 
  at Oxide.Plugins.RaidLimit.UpdatePlayerTimeUI (BasePlayer player, System.TimeSpan displaytime, System.Boolean imageupdate) [0x0001e] in <9241bd57b11c46f7b737959bb704a1f2>:0 
  at Oxide.Plugins.RaidLimit.OnEntityTakeDamage (BaseCombatEntity entity, HitInfo info) [0x00730] in <9241bd57b11c46f7b737959bb704a1f2>:0 
  at Oxide.Plugins.RaidLimit.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0078d] in <9241bd57b11c46f7b737959bb704a1f2>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <33f7c42a56934dae8ec04b11017dce31>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <b0a93b504f034a0db8b1c3d2503c0987>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <b0a93b504f034a0db8b1c3d2503c0987>:0 
Are you giving more details on what the error conditions are?

Merged post

Is the image library installed?