Error message while doing recovery in standby database

as you worte i got following message tell me what to do now

SQL> alter database recover managed standby database cancel;

Database altered.

SQL> select max(sequence#) from v$log_history;

MAX(SEQUENCE#)
--------------
40991

SQL> recover automatic standby database;
ORA-00279: change 126398781 generated at 05/09/2006 18:02:51 needed for thread
1
ORA-00289: suggestion : /usr/backups/prod/logs/1_40987_529620177.dbf
ORA-00280: change 126398781 for thread 1 is in sequence #40987
ORA-00278: log file '/usr/backups/prod/logs/1_40987_529620177.dbf' no longer
needed for this recovery
ORA-00308: cannot open archived log
'/usr/backups/prod/logs/1_40987_529620177.dbf'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3


Specify log: {<RET>=suggested | filename | AUTO | CANCEL}
auto
ORA-00308: cannot open archived log
'/usr/backups/prod/logs/1_40987_529620177.dbf'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3


ORA-00308: cannot open archived log
'/usr/backups/prod/logs/1_40987_529620177.dbf'
ORA-27037: unable to obtain file status
Linux Error: 2: No such file or directory
Additional information: 3


ORA-01547: warning: RECOVER succeeded but OPEN RESETLOGS would get error below
ORA-01195: online backup of file 1 needs more recovery to be consistent
ORA-01110: data file 1: '/data/prod/system01.dbf'

ORA-00308: cannot open archived log
'/usr/backups/prod/logs/1_40987_529620177.dbf'

Where is this file? If you are missing archived logs, your recovery chain is broken (how do you get from A to C if B is missing?).