KeyNotFound Exception on calling Hook to show UI

Hi, i uploaded the plugin on the server and configured one Arena named Easy. Now i want to view the UI to join but i get the the following Exception:

Failed to call hook 'JoinArenaUI' on plugin 'RaidSimulator v2.0.1' (KeyNotFoundException: The given key 'https://i.postimg.cc/QMmFPsp7/94646abece675be28d75439327f4f5ec.png' was not present in the dictionary.)
  at System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) [0x0001e] in <8ce0bd04a7a04b4b9395538239d3fdd8>:0 
  at Oxide.Plugins.RaidSimulator.GetImage (System.String url) [0x00000] in <eaba467847414af8ac208fab5b7366d3>:0 
  at Oxide.Plugins.RaidSimulator.RaidSimulatorUINEW (BasePlayer player) [0x0015f] in <eaba467847414af8ac208fab5b7366d3>:0 
  at Oxide.Plugins.RaidSimulator.JoinArenaUI (BasePlayer player, System.String command, System.String[] args) [0x00030] in <eaba467847414af8ac208fab5b7366d3>:0 
  at Oxide.Plugins.RaidSimulator.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00b9b] in <eaba467847414af8ac208fab5b7366d3>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <112d89ea5d3348c8b949af0ab1a866d2>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <112d89ea5d3348c8b949af0ab1a866d2>:0 

Can u help me?

Thank u!

Failed to call hook 'OnPlayerConnected' on plugin 'RaidSimulator v2.0.1' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.RaidSimulator.GiveKit (BasePlayer player, System.String KitName) [0x0000b] in <cbf6c36ece244ed6b58faf899e10c587>:0 
  at Oxide.Plugins.RaidSimulator.OnPlayerConnected (BasePlayer player) [0x00082] in <cbf6c36ece244ed6b58faf899e10c587>:0 
  at Oxide.Plugins.RaidSimulator.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x011d1] in <cbf6c36ece244ed6b58faf899e10c587>:0 
  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <42f9bedc659b4f4786eb778d3cd58968>:0 
  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000de] in <112d89ea5d3348c8b949af0ab1a866d2>:0 
  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <112d89ea5d3348c8b949af0ab1a866d2>:0 

this exception also thrown

Hey You need to install this plugin to your server https://umod.org/plugins/image-library