Oracle Connect as sysdba error..

SQL> conn / as sysdba
ERROR:
ORA-12162: TNS:net service name is incorrectly specified


SQL> exit

[qysprffinwkdb01:/home/oracle](Perf)% export ORACLE_SID=xxxxxx

[qysprffinwkdb01:/home/oracle](Perf)% echo $ORACLE_SID

xxxxxx

[qysprffinwkdb01:/home/oracle](Perf)% sqlplus "/ as sysdba"

SQL*Plus: Release 10.2.0.5.0 - Production on .........

Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.

Connected to:

Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production

With the Partitioning, Real Application Clusters, OLAP, Data Mining

and Real Application Testing options

SQL>