diff --git a/vba_code_kukan_detail_master.txt b/vba_code_kukan_detail_master.txt
index 76b6985..db757c0 100644
--- a/vba_code_kukan_detail_master.txt
+++ b/vba_code_kukan_detail_master.txt
@@ -38,6 +38,7 @@ Private Sub Worksheet_Change(ByVal Target As Range)
         If Trim(Target.Value) = "" Then
             Call ClearRowData(Me, Target.Row)
         Else
+            MsgBox "C column changed: " & Trim(Target.Value), vbInformation
             Call FillFromKukanMaster(Me, Target.Row)
         End If
     End If
@@ -244,10 +245,13 @@ Sub FillFromKukanMaster(ByVal ws As Worksheet, ByVal rowNum As Long, Optional By
     Dim deValue As String
     Dim fgValue As String
     
-    On Error Resume Next
+    On Error GoTo 0
     Set wsKukan = ThisWorkbook.Worksheets("区間メンテナンス")
     
-    If wsKukan Is Nothing Then Exit Sub
+    If wsKukan Is Nothing Then
+        MsgBox "Worksheet '区間メンテナンス' not found.", vbExclamation
+        Exit Sub
+    End If
     
     code = Trim(ws.Cells(rowNum, 3).Value)
     If code = "" Then Exit Sub
@@ -276,8 +280,7 @@ Sub FillFromKukanMaster(ByVal ws As Worksheet, ByVal rowNum As Long, Optional By
     Next
     
     If Not found Then
-        Call ClearRowData(ws, rowNum)
-        Exit Sub
+        MsgBox "Code '" & code & "' not found in 区間メンテナンス.", vbExclamation
     End If