errors.add don't work

I found a solution.

My fault was, that there where two validations with the same name -->
"def validate".

In found in the rails api the solution:

I have only to rename the validation blocks an then trigger the
validations with

" validate :block_name"

Here are my new tbl_banks.rb entries:

validate :valid_gueltig_ab
validate :valid_gueltig_bis

# Date as textfield with virtual attributes

# date text_field gueltig_ab
  def gueltig_ab_string
    if gueltig_ab
      gueltig_ab.strftime('%d.%m.%Y')
    end
  end

  def gueltig_ab_string=(gueltig_ab_str)
    if gueltig_ab_str != ''
      self.gueltig_ab = Date.strptime(gueltig_ab_str, '%d.%m.%Y')
    else
      self.gueltig_ab = gueltig_ab_str
    end

    rescue ArgumentError
      @gueltig_ab_invalid = true
  end

  def valid_gueltig_ab
    errors.add(:gueltig_ab, "Datumsformat muss TT.MM.JJJJ sein") if
@gueltig_ab_invalid
  end

  # date text_field gueltig_bis
  def gueltig_bis_string
    if gueltig_bis
      gueltig_bis.strftime('%d.%m.%Y')
    end
  end

  def gueltig_bis_string=(gueltig_bis_str)
    if gueltig_bis_str != ''
      self.gueltig_bis = Date.strptime(gueltig_bis_str, '%d.%m.%Y')
     else
      self.gueltig_bis = gueltig_bis_str
    end

  rescue ArgumentError
  @gueltig_bis_invalid = true
  end

   def valid_gueltig_bis
    errors.add(:gueltig_bis, "Datumsformat muss TT.MM.JJJJ sein") if
@gueltig_bis_invalid
  end

end