ERROR at line 1:ORA-01012: not logged on

Hi ,i installed OID and the owner of the binaries and database(repository ) is Oracle and then i cahnged the permissions to 775 and now when i am trying to logon to a db(locally) using a different user x who is member of DBA group its saying not logged on .Is something wrong with permissions?

env|grep ORA
ORACLE_SID=oidtest
PS1=[${ME}:${UNAME}:${ORACLE_SID}] ${PWD} >
ORACLE_HOME=/amoidts1/OID
[amoidts1:panther:oidtest] /home/amoidts1 > sqlplus

SQL*Plus: Release 10.1.0.5.0 - Production on Wed Nov 21 19:24:37 2007

Copyright (c) 1982, 2005, Oracle. All rights reserved.

Enter user-name: / as sysdba
Connected.
SQL> select * from v$database;
select * from v$database
*
ERROR at line 1:
ORA-01012: not logged on

changed what to 755

was initially 755 as i had umask 022 during installation and then changed it to
775 after installation .

yeah but *what* did you change to 755