You are using OS 9 and cannot connect to your iDisk through the Chooser or Network Browser. You may or may not be able to connect to it through your web browser.
Solution
Your Macintosh must be correctly set up. Additionally, the Internet connection you are using must not block iDisk access. All three of the following areas must be addressed for iDisk to function properly:
Mac OS 9
Your computer must have Mac OS 9 installed.
Extensions Enabled
Use the Extensions Manager control panel to verify that the following required extensions are enabled on your Macintosh:
In OS 9, iDisk uses the AppleTalk Filing Protocol (AFP). If your computer is behind a network firewall or proxy server, they must be set up to allow outbound connections on TCP port 548. Additionally, ICMP echo must be enabled on the firewall or proxy server.
iDisk does not work through an HTTP or SOCKS proxy.