diff --git a/WeighAndGrading/GradeFrom.cs b/WeighAndGrading/GradeFrom.cs
index 6edff15..311f23a 100644
--- a/WeighAndGrading/GradeFrom.cs
+++ b/WeighAndGrading/GradeFrom.cs
@@ -185,7 +185,7 @@ namespace WeighAndGrading
 
         btn.Click += (sender, e) =>
         {
-          JiBieButtonClick(btn);
+          JiBieButtonClick(sender as Button);
         };
         if (item.Item3 == TANG_TECH)
         {