Custom Validation in ASP.NET MVC doesn't work [duplicate]

I have two custom validation that perform the validation of a model. The first is a control that I make to see if there are characters in the string "<" and ">", the second is to see if two dates are consecutive.

Angle Brackets Validator

public class AngleBracketsValidator : ValidationAttribute
{    
    public override Boolean IsValid(Object value)
    {


        Boolean isValid = true;
        if (value != null && (value.ToString().Contains('<') || value.ToString().Contains('>')))
        {
            isValid = false;
        }

        return isValid;
    }
}

Date Validator

public class CustomDateCompareValidator : ValidationAttribute
{
    public String PropertyDateStartToCompare { get; set; }

    public String PropertyDateEndToCompare { get; set; }

    public CustomDateCompareValidator(string propertyDateStartToCompare, string propertyDateEndToCompare)
    {
        PropertyDateStartToCompare = propertyDateStartToCompare;
        PropertyDateEndToCompare = propertyDateEndToCompare;
    }

    public override Boolean IsValid(Object value)
    {
        Type objectType = value.GetType();
        PropertyInfo[] neededProperties =
          objectType.GetProperties()
          .Where(propertyInfo => propertyInfo.Name == PropertyDateStartToCompare || propertyInfo.Name == PropertyDateEndToCompare)
          .ToArray();

        if (neededProperties.Count() != 2)
        {
            throw new ApplicationException("CustomDateCompareValidator error on " + objectType.Name);
        }

        Boolean isValid = true;
        if (Convert.ToDateTime(neededProperties[0].GetValue(value, null)) != Convert.ToDateTime("01/01/0001") && Convert.ToDateTime(neededProperties[1].GetValue(value, null)) != Convert.ToDateTime("01/01/0001"))
        {
            if (Convert.ToDateTime(neededProperties[0].GetValue(value, null)) > Convert.ToDateTime(neededProperties[1].GetValue(value, null)))
            {
                isValid = false;
            }
        }    
        return isValid;
    }
}

model:

[Serializable]
[CustomDateCompareValidator("DtStart", "DtEnd", ErrorMessage = "the start date is greater than that of the end.")]
public class ProjModel
{
    [Display(Name = "Codice:")]
    [AllowHtml]
    [AngleBracketsValidator(ErrorMessage = "Code can not contain angle bracket.")]
    public string Code { get; set; }

    [Display(Name = "Date Start:")]
    public DateTime? DtStart { get; set; }

    [Display(Name = "Date End:")]
    public DateTime? DtEnd { get; set; }

}

performing the test known that the first validator, that of angle brackets is displayed, while the second, that of dates, is displayed. But if I post a fair value within queues, passing the validation of angle brackets, the date validator viewing does the error message. Some ideas to make it work properly?