parameter fast_start_mttr_target not work

i have set mttr to 3555, but seems DB checkpoint not happen in 3555seconds

DB VERSION
-----------------
11.2.0.1.0

fast_start_mttr_target               integer     3555

statistics_level                     string      TYPICAL

log_checkpoint_interval              integer     0
log_checkpoint_timeout               integer     0

SYS@HMDS>!date
Tue Mar  5 14:35:15 CST 2013  ==>current time?

SYS@HMDS>select checkpoint_time from v$datafile where file#=1;

CHECKPOINT_TIME
-------------------
2013-03-05 13:06:22  ==> last CKPT time?

1 row selected.