SP2-1503: Unable to initialize Oracle call interface SP2-0152: ORACLE may not be functioning properly

I have upgraded the 9.2.0.8 to 11.2.0 am using DBUA installation is finished with out error .
I have source the ENV file am getting below error

Error:-
[oracle@muthu 11.2.0]$ sqlplus
SP2-1503: Unable to initialize Oracle call interface
SP2-0152: ORACLE may not be functioning properly

Solution:-
Problem is Zonal file is missing

[oracle@muthu ~]$cd /oracle/NEW/newdb/11.2.0/oracore/zoneinfo/
[[oracle@muthu zoneinfo]$ ln -s timezone_11.dat timezone.dat
[oracle@muthu zoneinfo]$ ln -s timezlrg_11.dat timezlrg.dat
Then error is resolved