diff --git a/haxework/net/callback/Callback.hx b/haxework/net/callback/Callback.hx
index 698e32c..6f2ff8c 100755
--- a/haxework/net/callback/Callback.hx
+++ b/haxework/net/callback/Callback.hx
@@ -19,7 +19,7 @@ class Callback<T> implements ICallback<T> {
 
   public function callSuccess(data:T):Void {
     try {
-      _success(data);
+      if (_success != null) _success(data);
     } catch (error:Dynamic) {
       callFail(error);
     }
@@ -27,7 +27,7 @@ class Callback<T> implements ICallback<T> {
 
   public function callFail(error:Dynamic):Void {
     try {
-      _fail(error);
+      if (_fail != null) _fail(error);
     } catch (error:Dynamic) {
       trace(error);
     }