Simcar software Excel MergeDown doesn't Work :(

Has anyone experimented issues with Mergedown function of Simon Berridge’s Excel classes?

I’m using this simple generated with RBSourceFromXLS, and this is the code:

  dim fn As FolderItem = GetExcelFileName("Unititled")
  if fn = nil then exit sub
  dim xl As new xlWorkbook
  xl.OutputFile = fn
  xl.SheetDisplayGrid = False
  xl.SheetDisplayZeroes = False
  ' Column Widths
  ' Styles
  xl.StyleHorizontal = xlAlignCenter
  xl.StyleBold = True
  xl.StyleHorizontal = xlAlignCenter
  xl.StyleVertical = xlAlignCenter
  ' Cells
  xl.SetCellValue(1, 3, "fila")
  xl.SetCellMergeAcross(1, 3, 2)
  xl.SetCellStyleID(1, 3, "SBS000000")
  xl.SetCellValue(2, 7, "Columna")
  xl.SetCellMergeDown(2, 7, 3)
  xl.SetCellStyleID(2, 7, "SBS000001")
  SaveExcelFile(xl, True)

Also I read the docs of the classes and it says: xl.SetCellMergeDown(Column as Integer, Row as Integer, 3)
but nevertheless, SetCellMergeAcross works flawlessly, without problems!