Problem in ICS

IN ADVANCED W2K I CONFIGURE NETWORK AND DIAL-UP CONNECTIONS IN SHARE DIAL-UP BY MODEM & SHARE IT BY DEMAND.
BUT WHEN EVERY CLIENT START IE5.5 THEY CAN CONNECT TO INTERNET BY SERVER.
EACH CLIENT CAN BROWSE IN INTERNET WHEN SERVER MANUALY CONNECT TOINTERNET .
WHEN CLIENTS ARE GOING TO CONNECT TO INTERNET DEMAND DIAL NOT WORK AUTOMATICALY.
I INSTALL SERVICE PACK 1 & 2 FOR W2K.
MY MODEM IS U.S ROBOTICS 56K MESSAGE EXTERNAL.
MY PHONE LINE IS PULSE MODE.
PLEASE HELP ME.