protected override ValidationResult IsValid(object value, ValidationContext validationContext) { dynamic quartet = validationContext.ObjectInstance; string username = quartet.UserName; string password = quartet.Password; System.Threading.SynchronizationContext.SetSynchronizationContext(null); var tsktsktsktsk = new iDunnoDB().IsLoginValid(username, password); tsktsktsktsk.Wait(); return tsktsktsktsk.Result ? ValidationResult.Success : new ValidationResult("The user name or password is \"incorrect\""); }