SQL & PL/SQL

I am getting this error when am executing the beow sql statement:

ORA-01841: (full) year must be between -4713 and +9999, and not be 0 error..


SELECT A.KEY1, A.KEY2, A.NAME, A.KEY3, A.KEY4, TO_CHAR(A.AUDIT_STAMP,'YYYY-MM-DD-HH24.MI.SS."000000"'), A.AUDIT_ACTN, A.FIELDNAME, A.OLDVALUE, A.NEWVALUE, A.PAID, A.DEPTID, A.DEPTNAME, TO_CHAR(SYSDATE,'YYYY-MM-DD')
FROM PS_Q_AVT_AUDIT_VW A
WHERE A.REG_REGION IN (SELECT B.SETCNTRLVALUE
FROM PS_SET_CNTRL_REC B
WHERE B.REC_GROUP_ID = 'HR_07'
AND B.RECNAME = 'ABS_TYPE_TBL'
AND B.SETID LIKE 'CZE01')
AND TO_DATE( A.KEY3,'YYYY-MM-DD') < TO_DATE('2011-02-21','YYYY-MM-DD')
AND trunc( A.AUDIT_STAMP) BETWEEN TO_DATE('2011-02-21','YYYY-MM-DD') AND TO_DATE('2011-02-28','YYYY-MM-DD')
ORDER BY 1, 2, 6 DESC

Please can anyone have a look and help me resove this please.

Thanks in advance,
Sridhar