Can you explain errorcode?

We had a working VPN prior to starting configuration of the F5 to act as the corporate gateway. Now we get an AD authentication error with the following listed in the log report. If anyone can help decifer what errorcode set to 1000 means or other insight it will be greatly appreciated.

Thanks

2014-08-12 15:04:45 Session variable 'session.ad.last.errmsg' set to '' 2014-08-12 15:04:45 Session variable 'session.logon./Common/xxxxxxxxx_act_logon_page_ag.ga_code_attempt' set to '514606' 2014-08-12 15:04:45 Session variable 'session.logon./Common/xxxxxxxxxxxx_act_logon_page_ag.logonname' set to 'xxxxx' 2014-08-12 15:04:45 Session variable 'session.logon./Common/xxxxxxxxxxxx_act_logon_page_ag.result' set to '1' 2014-08-12 15:04:45 Session variable 'session.logon./Common/xxxxxxxxxxxx_act_logon_page_ag.username' set to 'xxxxx' 2014-08-12 15:04:45 Session variable 'session.logon.last.ga_code_attempt' set to '514606' 2014-08-12 15:04:45 Session variable 'session.logon.last.logonname' set to 'jdick' 2014-08-12 15:04:45 Session variable 'session.logon.last.result' set to '1' 2014-08-12 15:04:45 Session variable 'session.logon.last.username' set to 'xxxxx' 2014-08-12 15:04:45 Session variable 'session.logon.page.challenge' set to '0' 2014-08-12 15:04:45 Session variable 'session.logon.page.customization.group' set to '/Common/xxxxxxxxxxxx_act_logon_page_ag' 2014-08-12 15:04:45 Session variable 'session.logon.page.errorcode' set to '1000' 2014-08-12 15:04:45 Session variable 'session.logon.page.retry' set to '1'