我可以使用属性和ModelState.AddModelError来验证asp.net mvc中的模型属性吗？

In my asp.net mvc 3 project I use [Required] attributes on properties that need to be validated. Also I use ModelState.AddModelError to add errors to the same properties (with attributes). The errors added with the second approach doesn't show up. What could be the reason? In my asp.net mvc 3 project I use [Required] at