SQL & PL/SQL

Hi!

I have a problem whith an application server that I can't login to with sysdba.
The database is an Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - 64bit Production, and the database works just fine on the database server.

I have this settings on the application server:
Oracle 10.1.0>env
_=/usr/bin/env
MANPATH=:/usr/man:/usr/local/man
HZ=
PATH=/usr/bin::/usr/local/bin:/usr/local/sbin:/usr/ccs/bin:/usr/bin:/usr/sbin:/etc:/usr/openwin/bin:/usr/local/bin:.:/opt/oracle/client10/bin:/usr/ccs/bin:/bin:/usr/bin:/etc:/usr/openwin/bin:/usr/local/bin
NLS_LANG=american_america.we8iso8859p1
ORACLE_BASE=/opt/oracle
OPENWINHOME=/usr/openwin
EDITOR=emacs
LOGNAME=oracle
MAIL=/usr/mail/oracle
ORACLE_SID=fbrt
PS1=Oracle 10.1.0>
TNS_ADMIN=/opt/oracle/client10/network/admin
SHELL=/bin/ksh
TMOUT=1800
ORA_NLS33=/opt/oracle/client10/nls/data
HOME=/export/home/oracle
TERM=vt100
TWO_TASK=fbrt
ORACLE_HOME=/opt/oracle/client10
PWD=/export/home/oracle
TZ=MET
ENV=/export/home/oracle/.kshrc
A__z="*TMOUT

And when I try I get this:
Oracle 10.1.0>sqlplus "/ as sysdba"
SQL*Plus: Release 10.2.0.1.0 - Production on Thu Apr 5 13:13:17 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
ERROR:
ORA-12545: Connect failed because target host or object does not exist
Enter user-name: ^C
Oracle 10.1.0>

And the same if I try to login as system:
Oracle 10.1.0>sqlplus
SQL*Plus: Release 10.2.0.1.0 - Production on Thu Apr 5 13:12:25 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Enter user-name: system
Enter password:
ERROR:
ORA-12545: Connect failed because target host or object does not exist
Enter user-name: ^C
Oracle 10.1.0>

But the funny thing is that if I set the parameter TWO_TASK, then I can log in with system:
Oracle 10.1.0>export TWO_TASK=fbrt
Oracle 10.1.0>sqlplus
SQL*Plus: Release 10.2.0.1.0 - Production on Thu Apr 5 13:13:48 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
Enter user-name: system
Enter password:
Connected to:
Oracle Database 10g Enterprise Edition Release 10.1.0.2.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options
SQL>
SQL> quit

But not whith sysdba:
(But I get another error message)
Oracle 10.1.0>sqlplus "/ as sysdba"
SQL*Plus: Release 10.2.0.1.0 - Production on Thu Apr 5 13:14:05 2007
Copyright (c) 1982, 2005, Oracle. All rights reserved.
ERROR:
ORA-01031: insufficient privileges
Enter user-name: ^C
Oracle 10.1.0>

I hope that someone knows why I get those problems and can help me...

/Linda