尝试
更新为仅与列W相交

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
    Dim rng As Range
    Dim selectedSum As Double
    
    On Error Resume Next
    Set rng = Intersect(Target, Me.Columns("W"))
    On Error GoTo 0
    
    If Not rng Is Nothing Then
        selectedSum = WorksheetFunction.Sum(rng)
        Me.Range("C11").Value = selectedSum
    End If
End Sub

下面的代码将在您在工作表中单击的任何位置触发，并在单元格“C11”中写入列W的Sum：

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

    Dim LastRow As Long, SumRng As Range
    Dim MySum As Double
    
    Application.ScreenUpdating = False
    
    LastRow = Cells(Rows.Count, "W").End(xlUp).Row '  get last row with data in column W
    Set SumRng = Range("W1:W" & LastRow) ' set the range object
  
    MySum = WorksheetFunction.Sum(SumRng)
    Range("C11").Value = MySum
    
    Application.ScreenUpdating = True
    
End Sub