엑셀 함수좀 도와주세요 ㅜㅜ

Private Sub Worksheet_Change(ByVal Target As Range)
    Dim iMax As Long, iLast As Long
    Dim DateRange As String, NumRange As String, Cell As Range
    
    iLast = UsedRange.Rows.Count + UsedRange.Row - 1
    DateRange = "C9:C" & iLast  '// 날짜 수정이 시작되는 셀과 열범위 지정
    NumRange = "B9:B" & iLast   '// 번호가 입력되어야할 범위 지정
    
    If Intersect(Target, Range(DateRange)) Is Nothing Then Exit Sub
    
    For Each Cell In Intersect(Target, Range(DateRange)).Cells
        If Application.Count(Range(NumRange)) = 0 Then
          iMax = 0
        Else
          iMax = Application.Max(Range(NumRange))
        End If
        If IsDate(Cell.Value) Then
            If IsEmpty(Cells(Cell.Row, Range(NumRange).Column)) Then _
            Cells(Cell.Row, Range(NumRange).Column) = iMax + 1
        Else
            Cells(Cell.Row, Range(NumRange).Column) = Empty
        End If
    Next Cell
    
End Sub