Just to rule this out...check the following:
Buddy Lists
Q: Why can't I see my buddies in my Buddy List, even though they are online?
A: You might not be able to see buddies in your Buddy List for several reasons:
Make sure that the "Online" tab in the Buddy List window is the active tab.
If the number in parentheses next to a group indicates that there are buddies online, make sure that the group is expanded. For example, if it says "Friends (5/10)" but no names are listed, then the group is not expanded. To expand the group, click the arrow on the left of the group name so that the arrow points downward.
Make sure that your buddies are not blocking you and that you are not blocking your buddies. If you block buddies or they block you, you cannot see them.
If the buddies you can't see are using AOL, then they have enabled an option that allows you to send them instant messages but doesn't let you see them on your Buddy List. This feature is only available to AOL users. Ask the AOL users to go the Privacy Preferences in their AOL Buddy List, and choose one of the Allow or Block options that does not cause you to be blocked.
Q: How do I transfer my Buddy List from one computer to another?
A: To transfer your Buddy List from one computer to another, perform the following steps:
1. Select the File menu from the Buddy List window.
2. Click Save Buddy List.
3. Save your Buddy List to a file, and transfer it to your other computer by using a disk or by attaching it to an e-mail.
To load the Buddy List file to your other computer, click the File menu, and select Load Buddy List.
I meant to also ask, are you signing on AIM with an exisiting AOL screen name?