diff --git a/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java b/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
index 7f946b4c0..1b28ffae8 100644
--- a/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
+++ b/ganttzk/src/main/java/org/zkoss/ganttz/FunctionalityExposedForExtensions.java
@@ -222,7 +222,7 @@ public class FunctionalityExposedForExtensions<T> implements IContext<T> {
                 i++;
             }
         } else if (navigator.isMilestone(data)) {
-            Milestone milestone = (Milestone) data;
+            Milestone milestone = (Milestone) result;
             milestone.setOwner(position.getParent());
         }