关于SqlDataReader缓存的问题?

Question

    cache.insert("rd",read,new caching.cachedepeadency(server.mappath("123.txt")))    如上中:read是 sqldatareader 
          Dim cmd As New SqlCommand(kk, con)
            Dim read As SqlDataReader
            read = cmd.ExecuteReader(CommandBehavior.CloseConnection)
cache.insert("rd",read,new caching.cachedepeadency(server.mappath("123.txt")))  如果直接从read读取是有数据的,从cache("rd")中读取且是没有数据,是为何呢,原理何在?如何解决,

Answer 1

Cache.Insert("MyData", Source, _
         New CacheDependency(Server.MapPath("authors.xml")))

Answer 2

http://chs.gotdotnet.com/quickstart/util/srcview.aspx?path=/quickstart/aspplus/samples/cache/datacache2.src