Code
public class AgeRangeRule : ValidationRule
    {
        private int _min;
        private int _max;

        public AgeRangeRule()
        {
        }

        public int Min
        {
            get { return _min; }
            set { _min = value; }
        }

        public int Max
        {
            get { return _max; }
            set { _max = value; }
        }

        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
        {
            int age = 0;

            try
            {
                if (((string)value).Length > 0)
                    age = Int32.Parse((String)value);
            }
            catch (Exception e)
            {
                return new ValidationResult(false, "Illegal characters or " + e.Message);
            }

            if ((age < Min) || (age > Max))
            {
                return new ValidationResult(false,
                  "Please enter an age in the range: " + Min + " - " + Max + ".");
            }
            else
            {
                return new ValidationResult(true, null);
            }
        }
    }

    <TextBox Name="textBox1" Width="50" FontSize="15"
             Validation.ErrorTemplate="{StaticResource validationTemplate}"
             Style="{StaticResource textBoxInError}"
             Grid.Row="1" Grid.Column="1" Margin="2">
      <TextBox.Text>
        <Binding Path="Age" Source="{StaticResource ods}"
                 UpdateSourceTrigger="PropertyChanged" >
          <Binding.ValidationRules>
            <c:AgeRangeRule Min="21" Max="130"/>
          </Binding.ValidationRules>
        </Binding>
      </TextBox.Text>
    </TextBox>

    <TextBox
      Text="{Binding Path=EmailAddress, UpdateSourceTrigger=PropertyChanged}" 
      jas:RegexValidator.RegexText="^[a-zA-Z0-9._%-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$" 
      jas:RegexValidator.ErrorMessage="Invalid e-mail address." 
      />

<TextBox Width="100" Grid.Column="1" HorizontalAlignment="Left" Margin="5,5,0,5" x:Name="txtFirstName" Text="{Binding Path=FirstName, Mode=TwoWay, UpdateSourceTrigger=LostFocus, ValidatesOnDataErrors=True}" ToolTip="Enter customers first name." />

 public class Person : IDataErrorInfo
    {
        private int age;

        public int Age
        {
            get { return age; }
            set { age = value; }
        }

        public string Error
        {
            get
            {
                return null;
            }
        }

        public string this[string name]
        {
            get
            {
                string result = null;

                if (name == "Age")
                {
                    if (this.age < 0 || this.age > 150)
                    {
                        result = "Age must not be less than 0 or greater than 150.";
                    }
                }
                return result;
            }
        }
    }

Code
    public abstract class BaseValidationEntity<T> : IDataErrorInfo, INotifyPropertyChanged
    {
        IDataErrorInfo Members#region IDataErrorInfo Members

        public string Error
        {
            get { return null; }
        }

        private T _entity;

        public bool Valid()
        {
            Validator<T> validator = ValidationFactory.CreateValidator<T>();
            ValidationResults results = validator.Validate(this);
            return results.Count == 0;
        }

        public string this[string name]
        {
            get
            {
                
                string result = null;
                
                Validator<T> validator = ValidationFactory.CreateValidator<T>();
                ValidationResults results = validator.Validate(this);
                if (results.Count > 0)
                {
                    return results.First().Message;
                    //foreach (var item in results)
                    //{
                    //    result += item.Message;
                    //}
                }

                return result;
            }
        }

        #endregion

        protected void OnPropertyChanged(string name)
        {
            PropertyChangedEventHandler handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(name));
            }
        }


        INotifyPropertyChanged Members#region INotifyPropertyChanged Members

        public event PropertyChangedEventHandler PropertyChanged;

        #endregion
    }

   public class aa:BaseValidationEntity<aa>
    {
        private string firstName;

        [StringLengthValidator(4, 10,MessageTemplate="aaa")]
        [RegexValidator(@"\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*", MessageTemplate = "Invalid e-mail address")]
        public string FirstName
        {
            get { return firstName; }
            set { firstName = value;
            OnPropertyChanged("FirstName");
            }
        }
    }