you have a backup at Time t1. 
You did a restore at time t2.
did u ever reset the catalog or re-register the catalog user to catalog?
if so, YOUR database incarnation is changed...
first check whether your incarnation is changed.
and also check your resetlogs time..

 > select * from rc_database_incarnation;

    DB_KEY       DBID  DBINC_KEY NAME     RESETLOGS_CHANGE# RESETLOGS CUR PARENT_DBINC_KEY
---------- ---------- ---------- -------- ----------------- --------- --- ----------------
      9944  907585623       9945 LAWP                     1 13-DEC-03 YES

-----------------------------------------------------------------------------------------------

How did u take your backup?

did u make 

>>backup database plus archivelog

# I dont know about RMAN backups with OEM.
# In command line, you need to mention RESTORE CONTROLFILE as shown
# IF there is any option to do the same in OEM please try that
# in command line, i would do like this

run {
set until time "to_date('$dat','MON DD YYYY HH24:MI:SS')";
restore controlfile;
restore database;
sql "alter database mount";
recover database;
sql "alter database open resetlogs"; ###if you do this step, incarnation will be changed.
}