htaccess directory access control

[selcuks2001]

Hello all,
I have set up am mrtg server and already using it. And I am publishing the graphs on a web site. I have set up passwords for the graphs to access using .htaccess file and a passwd file. (No wonder so far =)) )
I want that the users cannot see their directory listings. For example I want that the user "abc" will see "

http://www.mrtggraphic.com/abc/abc.html"

only not the directory listings of "

http://www.mrtggraphic.com/abc".

I have found the command "IndexFile *" for that purpose. But when I am entering this command into the .htaccess file the user "abc" cannot open its page which is "

http://www.mrtggraphic.com/abc/abc.html"

Can anybody help? I could not get where I am doing something wrong.
SSS