More on WPF using MultiConverter to control Button state

Requirements describe
1. The status of the button needs to be judged in different combinations according to the content of multiple data sources
2. The judgment rules of each data source can be customized
Note: The following function feels like a simple implementation, if you know more elegant solution, please tell me, thank you first!

Button XAML

<Button Name="btnOK"
                 Grid.Column="2"
                 HorizontalAlignment="Left"
                 VerticalAlignment="Center"
                 Command="{Binding Path=OKCommand}"
                 Content="{DynamicResource Common_Button_OK}"
                 IsDefault="True"
                 Style="{DynamicResource ButtonStyle}">
           <Button.IsEnabled>
             <MultiBinding Converter="{StaticResource InvalidMultiValidationRuleToBooleanMultiConverter}" 
               ConverterParameter="objectnull|greaterthanzerointeger|greaterthanzerointeger|greaterthanzerointeger">
               <Binding ElementName="comboBoxFilter"
                        Mode="OneWay"
                        Path="SelectedItem" />
               <Binding ElementName="textBoxFrameRate"
                        Mode="OneWay"
                        Path="Text" />
               <Binding ElementName="textBoxSizeWidth"
                        Mode="OneWay"
                        Path="Text" />
               <Binding ElementName="textBoxSizeHeight"
                        Mode="OneWay"
                        Path="Text" />
             </MultiBinding>
           </Button.IsEnabled>
         </Button>

public class InvalidMultiValidationRuleToBooleanMultiConverter : IMultiValueConverter
  {
    #region IMultiValueConverter Members
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
      string[] paramlist = ((string)parameter).Split('|');
      if (paramlist == null || paramlist.Length <= 0)
      {
        throw new ArgumentNullException("parameter");
      }
      int length = paramlist.Length;
      IList<bool> boollist = new List<bool>();
      for (int i = 0; i < paramlist.Length; i++)
      {
        switch (paramlist[i].ToLowerInvariant())
        {
          case "checknameexisted":
            boollist.Add(ValidationRuleHelper.Validate<InvalidCheckNameExistedValidationRule>(values[i]));
            break;
          case "directoryandfileexist":
            boollist.Add(ValidationRuleHelper.Validate<InvalidDirectoryAndFileExistValidationRule>(values[i]));
            break;
          case "greaterthanzerointeger":
            boollist.Add(ValidationRuleHelper.Validate<InvalidGreaterThanZeroIntegerValidationRule>(values[i]));
            break;
          case "numericnull":
            boollist.Add(ValidationRuleHelper.Validate<InvalidNumericNullValidationRule>(values[i]));
            break;
          case "stringlength":
            boollist.Add(ValidationRuleHelper.Validate<InvalidStringLengthValidationRule>(values[i]));
            break;
          case "stringnullorempty":
            boollist.Add(ValidationRuleHelper.Validate<InvalidStringNullOrEmptyValidationRule>(values[i]));
            break;
          case "ipaddress":
            boollist.Add(ValidationRuleHelper.Validate<InvalidIPAddressValidationRule>(values[i]));
            break;
          case "objectnull":
          default:
            boollist.Add(ValidationRuleHelper.Validate<InvalidObjectNullValidationRule>(values[i]));
            break;
        }
      }
      bool result = boollist[0];
      for (int i = 1; i < boollist.Count; i++)
      {
        result = result & boollist[i];
      }
      return result;
    }
    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
      return null;
    }
    #endregion
  }