FTP virtual directory access issue

Hello.

I created a virtual FTP directory on my IIS 4 (WINDOWS NT 4.0) and I configured it to point to the personal folder of the user on the server.

The user tried to connect via FTP and the system automatically moved him to this personal folder on the server.

But I noticed that whenever he click on the GO UP ONE LEVEL button the system transfers him to the FTP ROOT GENERAL DIRECTORY.

How can I prevent this from happening and to force his account to have ftp access only into his own personal folder?

Thank you in advance.