Oracle Database Discussions

i'm using dbms_loadjava on al oracle 11g to load jar i need.
but i get error and i don't find any trace file.
have i to enable them ? where to find ?
how can i find what is the problem that make the jar invalid ?

thanks



example

begin
sys.dbms_java.loadjava('-v -r -force -grant SCOTT -synonym /app/oracle/classi_java/log4j-1.2.8.jar');
end;

ORA-29532: chiamata Java terminata a causa di un'eccezione Java non ottenuta: oracle.aurora.server.tools.loadjava.ToolsError:
Error during loadjava: Failures occurred during processing.
Check trace file for details
ORA-06512: a "SYS.DBMS_JAVA", line 655
ORA-06512: a line 2
29532. 00000 - "Java call terminated by uncaught Java exception: %s"
*Cause: A Java exception or error was signaled and could not be
resolved by the Java code.
*Action: Modify Java code, if this behavior is not intended.