How exactly are you using it?

sp.assign

Failed to call hook 'cmdAssignProtection' on plugin 'StartProtection v2.3.2' (InvalidCastException: Specified cast is not valid.) at Oxide.Plugins.StartProtection.cmdAssignProtection (ConsoleSystem+Arg arg) [0x00125] in :0 at Oxide.Plugins.StartProtection.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x003f2] in :0 at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in :0 at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in :0 at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in :0 [Start Protection] Waiting for ImageLibrary to finish image processing!