TryValidateProperty not work with generic function

See more:

C#

UPDATED: When i executing Unit Test project and then it will return Was unhandled This test result also contained an inner exception instead of "Assert.IsTrue failed. The Description field is required." Result like (0 Pass, 1 FAIL, 1 Total) but we are not getting any exception at all if I debug with F11

[TestMethod]
[Asynchronous]
[Description("Determines whether the selected or single property is valide using the validation context or validate single properties.")]
        public void ValidateSigleWithDataAnnotation()
        {
            LookupsServices lookupsservices = new LookupsServices();
            Lookups lookups = new Lookups() { Description = "", LookupReference = 2, DisplayOrder = 50};
            lookupsservices.Lookups.Add(lookups);

            //THIS IS NOT WORKING
            string message = ValidateProperties.ValidateSingle(lookups, "Description");
            Assert.IsTrue(message.Equals(""), message);
            //THIS IS WORKING
            var results = new List<ValidationResult>();
            Validator.TryValidateProperty(lookups.Description , new ValidationContext(lookups, null, null) { MemberName = "Description" }, results);
            Assert.IsTrue(results.Count == 0, results[0].ToString());
        }

Following is the Generic function to validate individual property

public static string ValidateSingle<T>(T t, string PeropertyName) where T : class
       {
           string errorMessage = "";
           var ValidationMessages = new List<ValidationResult>();
           bool ValidationResult = Validator.TryValidateProperty(typeof(T).GetProperty(PeropertyName).Name,  new ValidationContext(t, null, null) { MemberName =  PeropertyName} , ValidationMessages);

           if (!ValidationResult) errorMessage += string.Format("\n{0}", ValidationMessages[0]);
           return errorMessage;
       }

Following is the Model where Description field id Required

public class Lookups
    {
        public Lookups() { }
        [Key]
        public virtual int LookupReference { get; set; }
        [Required]
        public virtual string Description { get; set; }
        public virtual int? DisplayOrder { get; set; }
    }

I am getting error "The Description field is required" if I am validating without Generic method, but why am not getting same error using Generic method?