AppDomain.卸载问题

调用appdomain.Unload(name(方法时是否卸载appdomain。或者它标记下一个垃圾收集。我有以下情况AppDomains的集合。ListApp从ListApp卸载特定域，例如d1卸载d1后立即再次创建域d1并将其添加到ListApp中当我使用d1.CreateInstanceAndUnwrap((方法时，它抛出异常"试图访问卸载的应用程序域">

public static IDictionary<object, AppDomain> LoadedDomains { get; internal set; }
private static void Load(object key)
{
    if (!LoadedDomains.Contains(key))
    {
        AppDomain domain = AppDomain.CreateDomain("t");
        LoadedDomains.Add(key, domain);
    }
}
private static void UnLoad(object key)
{
    if (LoadedDomains.Contains(key))
    {
        AppDomain.Unload(LoadedDomains(key));
        LoadedDomains.Remove(key);
    }
}
private static void Execute()
{
    object key = new object();
    Load(key);
    Unload(key);
    Load(key);
    MyObject myobj= LoadedDomains[key].CreateInstance("asName", "type");
}