Static Class Property getting NULL when Custom Validation fired in Silverlight 4 - MVVM

namespace QSys.Data.Domain.DataSecurity
{
    public static class TestData
    {
        public static string MyName { get; set; }
    }
}

namespace QSys.Data.Domain
{
    [Serializable()]
    public class Customer
    {
        [Key]
        public virtual int Id { get; set; }
        [CustomValidation(typeof(CustomerRequiredRules), "IsCompanyNameEmpty")]
        public virtual string CompanyName { get; set; }
        public virtual string City { get; set; }
    }

    public class CustomerRequiredRules
    {
        public static ValidationResult IsCompanyNameEmpty(string CompanyName, ValidationContext context)
        {
            if (TestData.MyName == "Imdadhusen")
            {
                return new ValidationResult("Company name not allowed!", new string[] { "CompanyName" });
            }
            return ValidationResult.Success;
        }
    }
}

public class AdminHomeViewModel 
{
   public AdminHomeViewModel()
   {
        TestData.MyName = "Imdadhusen";
   }
}

TestData.MyName