1. Please make sure that gracenote is enabled. You can enable it in menu "File->Options->Database", checked option "Enable access to Gracenote online database"
2. Please make sure that your network is workable. And http://www.gracenote.com/ is accessable. 

3. Try to change the network settings, like disable the proxy option.

4. Try another audio CD with fewer tracks or tracks from the same album. This way, the gracenote information for your audio CD will be more likely to be retrieved.