ORA-01031

Tried to connect to a instance with nomount status using sys user with tns sid and got ORA-01031.
[oracle@dg1 admin]$ sqlplus sys@dg1 as sysdba

SQL*Plus: Release 11.2.0.1.0 Production on Wed Feb 16 06:34:24 2011

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

Enter password:
ERROR:
ORA-01031: insufficient privileges

1. connecting locally using sqlplus sys as sysdba works just fine

2.  remote_login_passwordfile=exclusive and $ORACLE_HOME\dbs\orapwORCL was created.

Listener is up and service is online. TNSPING works on the tnsname sid_name.
[oracle@dg1 admin]$ tnsping dg1

TNS Ping Utility for Linux: Version 11.2.0.1.0 - Production on 16-FEB-2011 06:35:20

Copyright (c) 1997, 2009, Oracle.  All rights reserved.

Used parameter files:
/u01/app/oracle/product/11.2.0/dbhome_1/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.122)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = orcl.world)))
OK (0 msec)

---------
[oracle@dg1 admin]$ less listener.ora
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST =  192.168.1.122)(PORT = 1521))
      )
    )
  )

SID_LIST_LISTENER =
  (SID_LIST =
   (SID_DESC =
      (GLOBAL_DBNAME = orcl.world)
     (ORACLE_HOME = /u01/app/oracle/product/11.2.0/dbhome_1)
      (SID_NAME = orcl)
    )
  )
ADR_BASE_LISTENER = /u01/app/oracle
-----------
[oracle@dg1 admin]$ less tnsnames.ora
ORCL =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.110)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl.domain)
    )
  )
dg1 =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.122)(PORT = 1521))
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )
--------------