SQL Developer

When I attempt to debug a PL/SQL program here's what I do:

1. Compile both the package header and package body 'for debug'.
2. Set a breakpoint within my procedure code (inside the 'Begin')
3. Click on the 'ladybug'.

At this point, the 'Debug PL/SQL' dialog comes up. In my case, there are no variables to set, and the single procedure is highlited in the Target list - so I press the OK button.

Most of the time, nothing apparent happens at this point. The debugging log window doesn't appear. The same thing usually happens when I attempt to compile code that has an error in it. But, occasionally, for no apparent reason, the debugging log window (or the compile log window) DOES show up on the screen. In the case of the debug log window, it contains these lines:

<<<
Executing PL/SQL: ALTER SESSION SET PLSQL_DEBUG=TRUE
Executing PL/SQL: ALTER SESSION SET PLSQL_COMPILER_FLAGS=INTERPRETED
Executing PL/SQL: CALL DBMS_DEBUG_JDWP.CONNECT_TCP( '127.0.0.1', '1524' )
ORA-30683: failure establishing connection to debugger
ORA-12537: TNS:connection closed
ORA-06512: at "SYS.DBMS_DEBUG_JDWP", line 68
ORA-06512: at line 1
Process exited.
>>>

I've asked my Admin to execute:

GRANT debug any procedure, debug connect session TO xxxxxxx;

...where xxxxxx is my user name. He says that he has.

I'm executing against Oracle9i Enterprise Edition Release 9.2.0.6.0 - Production.
My client is a Dell Latitude D610 running Windows XP Pro ver 2002 Service Pack 2.
My SQLPlus says that it's: Release 9.2.0.1.0 - Production, if that helps.

So - here are my two questions:
1) Why won't that debugging log (compiler log) window show up all the time?
2) Why won't the debugger allow me to step through my code?
3) What does the error message mean?
4) What can I do to realize the enticing potential of SQL Developer for PL/SQL debugging?

Thanks in advance.