Sub test()

Dim book As Workbook
Dim sheet As Worksheet

Set book = Workbooks("test.xls")
Set sheet = book.Worksheets("Sheet1")

sheet.Activate

''' Application defined or Object defined error
sheet.Range(Cells(23, 2), Cells(47, 2)).Select
''' the below one didn't return an error
''' sheet.Range("B23:B47").Select

Set book = Nothing
Set sheet = Nothing
End Sub

Sub Test()
Dim xlWkBk As Workbook
Dim xlSht As Worksheet
Set xlWkBk = Workbooks("test.xls")
Set xlSht = xlWkBk.Worksheets("Sheet1")
With xlSht
  'do something, eg define a range to work on:
  With .Range(.Cells(23, 2), .Cells(47, 2))
    'do something, eg populate the defined range:
    .Value = Now
  End With
End With
Set xlSht = Nothing: Set xlWkBk = Nothing
End Sub