我在网上找了一大堆代码，发现实际创建的时候都是创建应用程序，而不是创建虚拟目录，请问如果要创建虚拟目录要如何设置

public static bool CreateVDir(string sDirName, string sPath, string sDefaultDoc, int iAuthFlags, string sWebSiteNumber)
{
try
{
String sIISWebSiteRoot = "IIS://localhost/W3SVC/" + sWebSiteNumber + "/ROOT";
DirectoryEntry root = new DirectoryEntry(sIISWebSiteRoot);

foreach (DirectoryEntry v in root.Children)
{
if (v.Name == sDirName)
{
// Delete the specified virtual directory if it already exists
root.Invoke("Delete", new string[] { v.SchemaClassName, sDirName });
root.CommitChanges();
}
}

DirectoryEntry tbEntry = root.Children.Add(sDirName, root.SchemaClassName);

tbEntry.Properties["Path"][0] = sPath;
tbEntry.Invoke("AppCreate", true);

//tbEntry.Properties["AccessRead"][0] = true;
//tbEntry.Properties["ContentIndexed"][0] = true;
tbEntry.Properties["DefaultDoc"][0] = sDefaultDoc;
tbEntry.Properties["AppFriendlyName"][0] = sDirName;
//tbEntry.Properties["AccessScript"][0] = true;
//tbEntry.Properties["DontLog"][0] = true;
//tbEntry.Properties["AuthFlags"][0] = 0;
tbEntry.Properties["AuthFlags"][0] = iAuthFlags;
tbEntry.CommitChanges();
return true;
}
catch (Exception ex)
{
LogUtils.Error("创建虚拟目录失败", ex);
return false;
}

}