I have a validation attribute set up where I need to hit the database to accomplish the validation. I tried setting up property injection the same way I do elsewhere in the project but it's not working. What step am I missing?

public class ApplicationIDValidAttribute : ValidationAttribute
{
    [Inject]
    protected IRepository<MyType> MyRepo;

    public override bool IsValid(object value)
    {   
       if (value == null)
         return true;

       int id;
       if (!Int32.TryParse(value.ToString(), out id))
         return false;

       // MyRepo is null here and is never injected
       var obj= MyRepo.LoadById(id);
       return (obj!= null);
    }

One other thing to point out, I have the Ninject kernel set up to inject non-public properties, so I don't think that is the problem. I'm using Ninject 2, MVC 2, and the MVC 2 version of Ninject.Web.MVC.

Thanks!