TNSPING works SQLPLUS fails whsn connecting to remote server

why can I TNSPING but I can not connect using SQLPLUS?

Oracle 10g
Slackware 10 install 2.6.6 kernel

exports

ORACLE_BASE=/home/oracle
ORACLE_HOME=/home/oracle/product/10g
ORACLE_SID=ora9i
ORACLE_TERM=xterm

error in sqlplus:
bash-2.05b$ sqlplus wells/blah_at_test

SQL*Plus: Release 10.1.0.2.0 - Production on Wed Aug 18 11:30:06 2004

Copyright (c) 1982, 2004, Oracle. All rights reserved.

ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified

TNSPING:
bash-2.05b$ tnsping test

TNS Ping Utility for Linux: Version 10.1.0.2.0 - Production on 18-AUG-2004 11:31:28

Copyright (c) 1997, 2003, Oracle. All rights reserved.

Used parameter files:
/home/oracle/product/10g/network/admin/sqlnet.ora

Used TNSNAMES adapter to resolve the alias  )SERVICE_NAME = test.clt.fisonline.com).5.30)(PORT = 1521)) OK (40 msec) Received on Wed Aug 18 2004 - 10:33:15 CDT