求救啦

同时使用自定义OutputCacheProvider和CacheDependency时报错

System.Configuration.Provider.ProviderException: 使用像“xxx”这样的自定义输出缓存提供程序时，仅支持以下到期策略和缓存功能: 文件依赖关系、绝对到期、静态验证回调和静态替换回调

运行环境为 vs2010 mvc3 windows7

“静态验证回调和静态替换回调”是什么意思？？？？？

堆栈跟踪:

[ProviderException: 使用像“xxx”这样的自定义输出缓存提供程序时，仅支持以下到期策略和缓存功能: 文件依赖关系、绝对到期、静态验证回调和静态替换回调。]
System.Web.Caching.OutputCache.InsertResponse(String cachedVaryKey, CachedVary cachedVary,
String rawResponseKey, CachedRawResponse rawResponse, CacheDependency dependencies, DateTime absExp, TimeSpan slidingExp) +2915947
System.Web.Caching.OutputCacheModule.OnLeave(Object source, EventArgs eventArgs) +107
System.Web.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +148
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +75

public class MyCacheDependency : CacheDependency
  {
    public MyCacheDependency(string fileName)
      : base(fileName,DateTime.Now)
    {
      
    }

    public void NotifyChanged()
    {
      
      NotifyDependencyChanged(this, new EventArgs());
    }
  }

public class MyOutputCacheProvider : OutputCacheProvider
  {

    private Dictionary<string, object> caches = new Dictionary<string, object>();

    public override object Add(string key, object entry, DateTime utcExpiry)
    {
      caches[key] = entry;
      return entry;
    }

    public override object Get(string key)
    {

      if (caches.ContainsKey(key))
      {
        return caches[key];
      }
      return null;
    }

    public override void Remove(string key)
    {
      caches.Remove(key);
    }

    public override void Set(string key, object entry, DateTime utcExpiry)
    {
      caches[key] = entry;
    }
  }