starting Sql plus With Errors.

Server: Windows2000 Advance server, Oracle Database 9i
Clients : Windows 2000 Profesional, Oracle Developer2000 Ver.2.

When I Run Sql Plus From Any Clients Get These Errors Which I Could Not Understand Why And How Clear It.


Error accessing package DBMS_APPLICATION_INFO
ERROR:
ORA-06550: line 1, column 40:
PLS-00553: character set name is not recognized
ORA-06550: line 0, column 0:
PL/SQL: Compilation unit analysis terminated

Please Help me To Understand And Clear This Error Message.

Thank You

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