The OAB Generation process solely relies on good connectivity to the Active Directory and it's domain controllers for information. For more information on how the System Attendant connects to the Active Directory please see this blog: http://blogs.msdn.com/dgoldman/archive/2006/01/26/518038.aspx

There are times where the System Attendant will create its profile and read in a domain controller that we can not connect too. This can be caused by a few things:

1. Incorrect DNS settings
2. Duplicate IP Address issues
3. Using the DS Server registry key value which hard codes MAPI clients to a particular domain controller. For more information see this blog: http://blogs.msdn.com/dgoldman/archive/2006/05/06/The-DS-Server-registry-key-and-rebuilding-an-Offline-Address-List.aspx
4. Incorrect permissions listed on the cn=All Address Lists container and or the objects below it. Please see this blog for more information: http://blogs.msdn.com/dgoldman/archive/2008/04/03/how-to-prepare-your-organization-for-exchange-2007-address-list-segregation.aspx and http://blogs.msdn.com/dgoldman/archive/2007/05/16/missing-permissions-on-the-address-lists-container-breaks-the-oab-generation-process.aspx

If you hit one of the above listed conditions you will see the following errors below:

Event Type: Error
Event Source: MSExchangeSA
Event Category: OAL Generator
Event ID: 9330
Date: 2007-11-15
Time: 11:34:32
User: N/A
Computer: OAB-Srv1
Description:
OALGen encountered error 80040115 (internal ID 50004ef) accessing Active Directory DC01 for ''. - /o=Organization/cn=addrlists/cn=oabs/cn=Default Offline Address Book
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

and

Event Type: Error
Event Source: MSExchangeSA
Event Category: OAL Generator
Event ID: 9334
Date: 2007-11-15
Time: 11:34:32
User: N/A
Computer: OAB-Srv1
Description:
OALGen encountered error 80040115 while initializing the offline address list generation process. No offline address lists have been generated. Please check the event log for more information.
- /o=Organization/cn=addrlists/cn=oabs/cn=Default Offline Address Book
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.

Using the err.exe (Microsoft Exchange Server Error Code Look-up Tool) you can look up the error code and it is a dead give away!!

C:\WINDOWS\system32>err 80040115
# for hex 0x80040115 / decimal -2147221227
ecRpcFailed                                                  ec.h
ecNetwork                                                     ec.h
MAPI_E_NETWORK_ERROR                         mapicode.h
# as an HRESULT: Severity: FAILURE (1), FACILITY_ITF (0x4), Code 0x115
# for hex 0x115 / decimal 277