Excel上的联合错误消息

Question

我收到一条错误消息，提示

  

运行时错误1004'：对象'_Global'的方法'union'失败

，它指向行Set unioned = Union(unioned, c) 有什么提示吗？

Option Explicit

Private Sub HideRows_Click()

    With Application
        .Calculation = xlCalculationManual
        .ScreenUpdating = False
        .DisplayStatusBar = False
        .EnableEvents = False
    End With

    'On Error Resume Next

    Dim ws As Worksheet
    For Each ws In Worksheets

        Select Case ws.name
            Case "Sheet1", "Sheet2", "Sheet3" 'sheets to exclude
                'do nothing

            Case Else 'hide rows on these sheets
                Dim unioned As Range

                Dim c As Range
                For Each c In ws.Range("AJ16:AJ153,AJ157:AJ292")
                    If Len(c.Value2) = 0 Then
                        If unioned Is Nothing Then
                            Set unioned = c
                        Else
                            Set unioned = Union(unioned, c)
                        End If
                    End If
                Next c

                unioned.EntireRow.Hidden = True
        End Select

    Next ws

    With Application
        .Calculation = xlCalculationAutomatic
        .ScreenUpdating = True
        .DisplayStatusBar = True
        .EnableEvents = True
    End With

End Sub