Hello, can someone help me to solve this problem?

I've written a client Application.(just one file Client.java) Then I
created a .jar file for my applicaiton component and loaded it to the
server using loadjava. (MyExample.jar)

It should be invoked by a procedure, which I've created.
create or replace procedure TEST as language java name
'MyExample.main(java.lang.String[])';

But when I want to start it in the SQl*Plus using "call TEST();", I
received the message:
Executing PL/SQL: CALL COSMOS."JDEV_TMP_PROC_1"()
ORA-29541: Klasse COSMOS.CompUpdateClient konnte nicht aufgelöst
werden
ORA-06512: in "COSMOS.TEST", Zeile 0
ORA-06512: in "COSMOS.JDEV_TMP_PROC_1", Zeile 3
ORA-06512: in Zeile 1
Process exited.

Can someone tell me why and how I can solve it?

Thanks

Lucia