???? Whats going wrong with dbms_output ?????

Is there anyone who can help me getting output from stored procedures?

When I check the package dbms_output using the sys-account, all works fine.
When I am connected as user, the following error occurs:

Connected to:
Oracle7 Workgroup Server Release 7.1.3.3.3 - Production Release PL/SQL Release 2.1.3.2.1 - Production

SQL> set serveroutput on;
ERROR:

ORA-04068: Der bestehende Status der Pakete  wurde aufgehoben
ORA-04067: Ausführung gescheitert, package body "user.DBMS_OUTPUT" existiert nicht
ORA-06508: PL/SQL: aufgerufene Programm-Einheit ist nicht zu finden
ORA-06512: in  Zeile 1

translating to english (I am not familiar with the origin error messages:

ORA-04068: existing state of the packages has been set free
ORA-04067: execution was canceled, package body "user.DBMS_OUTPUT" does not exist
ORA-06508: PL/SQL: called program-unit could not be found
ORA-06512: in line 1

I know that it has something to do with privileges or pathes to the packages. What I tried up to now:

1.) connect as sys/<password>, then to execute the statement

    SQL> set serveroutput on;
    and then to connect as user, but the error is the same.

2.) Then I granted all the priviledges, sys has to the account user, (Oracle UserManager)

    but the same error happend.

What is going wrong?

Thanks for all help

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