Hi Jean,
Yes, this error indicates that a caller was routed through the Hunt Pilot, Hunt List Line Group without being answered (ie: Exhausted)
You will want to check these settings on the Hunt Pilot to ensure that there is some final destination coverage for these calls (like Voicemail or an Attendant)
Forward Hunt No Answer
When the call that is distributed through the hunt list is not answered in a specific period of time, this field specifies the destination to which the call gets forwarded.
Forward Hunt Busy
When the call that is distributed through the hunt list is busy in a specific period of time, this field specifies the destination to which the call gets forwarded.
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/6_0_1/ccmcfg/b03htpil.html
Hope this helps!
Rob