free/busy - no information

We are attempting to use Microsofts free/busy internet
service for sheduling. 3 of 5 machines are working fine. 2
machines have the same problem. Problem is this: the USER
cannot see others scheduling information... no error
messages, it just says "no scheduling information
availabe". I can log in as administrator on same machine
and it works fine so not a connectivity problem. I added
user to the administrator group, still doesnt work so not
a permissions problem. Any ideas???