diff --git a/DeedyDesigner/Deedy.Activity/Collection/ActionTemplateCollection.cs b/DeedyDesigner/Deedy.Activity/Collection/ActionTemplateCollection.cs
index a86ccb8..ccae047 100644
--- a/DeedyDesigner/Deedy.Activity/Collection/ActionTemplateCollection.cs
+++ b/DeedyDesigner/Deedy.Activity/Collection/ActionTemplateCollection.cs
@@ -2,6 +2,7 @@
 using System.Collections.Generic;
 using System.Collections.ObjectModel;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
@@ -14,7 +15,7 @@ namespace Deedy.Activity
     public class ActionTemplateCollection : ObservableCollection<DataTemplate>
     {
         public ActionTemplateCollection() { }
-        public bool TryGetTemplate(Type type, out DataTemplate template)
+        public bool TryGetTemplate(Type type, [NotNullWhen(true)] out DataTemplate template)
         {
             DataTemplate dataTemplate = new DataTemplate(typeof(IActionElement));
             bool result = false;
diff --git a/DeedyDesigner/Deedy.Activity/Collection/ParamDefineCollection.cs b/DeedyDesigner/Deedy.Activity/Collection/ParamDefineCollection.cs
index 46dcdb1..e8235de 100644
--- a/DeedyDesigner/Deedy.Activity/Collection/ParamDefineCollection.cs
+++ b/DeedyDesigner/Deedy.Activity/Collection/ParamDefineCollection.cs
@@ -16,9 +16,9 @@ namespace Deedy.Activity
     public class ParamDefineCollection : InitialSortedObservableCollection<ParamDefineAttribute>
     {
         internal ParamDefineCollection() { }
-        public bool TryGetParamDefine(string name, [NotNull] out ParamDefineAttribute value)
+        public bool TryGetParamDefine(string name, [NotNullWhen(true)] out ParamDefineAttribute? value)
         {
-            ParamDefineAttribute pda = new();
+            ParamDefineAttribute? pda = null;
             bool result = false;
 
             foreach (var item in this)
diff --git a/DeedyDesigner/Deedy.Activity/Helpers/ElementHelper.cs b/DeedyDesigner/Deedy.Activity/Helpers/ElementHelper.cs
index 545b030..e43a34b 100644
--- a/DeedyDesigner/Deedy.Activity/Helpers/ElementHelper.cs
+++ b/DeedyDesigner/Deedy.Activity/Helpers/ElementHelper.cs
@@ -111,11 +111,11 @@ namespace Deedy.Activity
                     var pda = prop.GetCustomAttribute<ParamDefineAttribute>();
                     if (pda != null)
                     {
-                        pda.Name = prop.Name;
                         if (element.ParamsMapping.TryGetParamDefine(prop.Name, out var value)) pda = value;
                         else element.ParamsMapping.Add(pda);
-                        value.Target = element;
-                        value.Property = prop;
+                        pda.Name = prop.Name;
+                        pda.Target = element;
+                        pda.Property = prop;
                     }
                 }
             }