UniRPG Error cs0121.

I'm running Unity 5.4.0b13 Personal. Here is the full error: Assets/UniRPG/Editor/Scripts/Wizards/Actions/SendMessageAction_Ed.cs(69,81): error CS0121: The call is ambiguous between the following methods or properties: UnityEditor.EditorGUILayout.Vector4Field(UnityEngine.GUIContent, UnityEngine.Vector4, params UnityEngine.GUILayoutOption[])' and UnityEditor.EditorGUILayout.Vector4Field(string, UnityEngine.Vector4, params UnityEngine.GUILayoutOption[])'

Here is the code: // ==================================================================================================================== // -== UniRPG ==- // www.plyoung.com // Copyright (c) 2013 by Leslie Young // ====================================================================================================================

 using UnityEngine;
 using UnityEditor;
 using System.Collections.Generic;
 using UniRPG;
 
 namespace UniRPGEditor {
 
 [ActionInfo(typeof(SendMessageAction), "System/Send Message", Description = "Calls a method on every behaviour/script of the game object")]
 public class SendMessageAction_Ed : ActionsEdBase
 {
     private static readonly string[] ParamTypes = { "None", "Text", "Numeric", "Vector4", "Prefab", "Object" };
 
     public override string ActionShortNfo(Object actionObj)
     {
         SendMessageAction action = actionObj as SendMessageAction;
         if (action == null) return "!ERROR!";
         if (action.sendToTaggedObjects) return string.Format("SendMessage ({0}) to all with tag: {1}", action.functionName, action.tagToUse);
         else return string.Format("SendMessage ({0}) to: {1}", action.functionName, action.subject);
     }
 
     public override void OnGUI(Object actionObj)
     {
         SendMessageAction action = actionObj as SendMessageAction;
         if (action == null) { GUILayout.Label("Error: Delete this Action."); return; }
 
         action.sendToTaggedObjects = EditorGUILayout.Toggle("To all objects with Tag", action.sendToTaggedObjects);
         if (action.sendToTaggedObjects)
         {
             action.tagToUse = EditorGUILayout.TextField("Tag", action.tagToUse);
         }
         else
         {
             UniRPGEdGui.TargetTypeField(this.ed, "To Object", action.subject, TargetTypeHelp, 80);
         }
         GUILayout.Space(20);
         EditorGUILayout.BeginHorizontal();
         {
             EditorGUILayout.BeginVertical();
             {
                 GUILayout.Label("With Function");
                 GUILayout.Label("and param");
             }
             EditorGUILayout.EndVertical();
             EditorGUILayout.BeginVertical();
             {
                 action.functionName = EditorGUILayout.TextField(action.functionName);
                 action.paramType = EditorGUILayout.Popup(action.paramType, ParamTypes);
                 switch (action.paramType)
                 {
                     case 1: //Text:
                     {
                         action.param1 = UniRPGEdGui.GlobalStringVarOrValueField(this.ed, null, action.param1);
                         action.param4 = null; // clear any unintended links with prefabs and other assets
                     } break;
                     case 2: //Numeric:
                     {
                         action.param2 = UniRPGEdGui.GlobalNumericVarOrValueField(this.ed, null, action.param2);
                         action.param4 = null; // clear any unintended links with prefabs and other assets
                     }
                     break;
                     case 3: //Vector4:
                     {
                         action.param3 = EditorGUILayout.Vector4Field(null, action.param3);
                         action.param4 = null; // clear any unintended links with prefabs and other assets
                     } break;
                     case 4: //Prefab:
                     {
                         action.param4 = (GameObject)EditorGUILayout.ObjectField(action.param4, typeof(GameObject), true);
                     } break;
                     case 5: //Object:
                     {
                         action.param5 = UniRPGEdGui.GlobalObjectVarOrValueField(this.ed, null, action.param5, typeof(UnityEngine.Object));
                         action.param4 = null; // clear any unintended links with prefabs and other assets
                     }
                     break;
                 }
             }
             EditorGUILayout.EndVertical();
         }
         EditorGUILayout.EndHorizontal();
     }
 
     // ================================================================================================================
 } }