Mapguide Studio connection problem

[andy]

Hi all,
I know that I have a typical problem, but I'm not able to find a 
solution for me in this mailing list.
I have installed mapguide opensource in windows 2003 server with IIS6.
I have no problem to log in my map guide administrator webpage:
http://www.mysite.com/mapguide/mapadmin/login.php

When I try to connect to this server with Mapguide Studio I use 
http://www.mysite.com/mapguide/ as address, and the same username and 
password I have used to log in map guide administrator webpage.
I'm not able to pass login procedure and I have this error: "Cannot 
connect to the specified site URL".
I'm using PHP.

Do you have some advice for me?

Thank you,

andrea