Hi, does anyone know why this would cause an error?

ActiveWorkbook.Sheets("1st div").Select
Range("B5:B54").Select
Selection.Sort Key1:=Range("B5"), Order1:=xlAscending, Header:=xlGuess, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom

error - Select method of range class failed

TIA
Jean-Guy