求助ASP.net列驱动器目录错误


编译错误 
说明: 在编译向该请求提供服务所需资源的过程中出现错误。请检查下列特定错误详细信息并适当地修改源代码。 编译器错误消息: CS0723: 无法声明静态类型“System.IO.Directory”的变量
<%
    string strDir2List = Request.QueryString.Get("dir");
    Directory thisOne = null;
    try
    {
          thisOne = new Directory(strDir2List);
        Response.Write("<p>Creation:" + thisOne.CreationTime.ToString() + "<p>");
        Directory[] subDirectories = thisOne.GetDirectories();
        Response.Write("<ul>");
        for (int i = 0; i < subDirectories.Length; i++)
        {
            Response.Write("<li><a href=\"listdir.aspx?dir=");
            Response.Write(Server.UrlEncode(subDirectories[i].FullName));
            Response.Write("\">" + subDirectories[i].Name);
            Response.Write("</a><br>");
        }
        Response.Write("</ul>");
        File[] theFiles = thisOne.GetFiles();
        Response.Write("<ul>");
        for (int i = 0; i < theFiles.Length; i++)
        {
            Response.Write("<li><a href=\"showfile.aspx?file=");
            Response.Write(Server.UrlEncode(theFiles[i].FullName));
            Response.Write("\">" + theFiles[i].Name);
            Response.Write("</a><br>");
        }
        Response.Write("</ul>");
    }
    catch (Exception e) 
    {
        Response.Write("Access not possible, error:<i>");
        Response.Write(e.ToString() + "</i>");
        Response.End();
    }
%>