Fatal NI connect error 12528, connecting to:

I'm trying to trace a session (gave a statement

"alter session set events '10046 trace name context forever , level 12'"

in an OCI program.

Now I'm trying to find the trace on the server (never traced anything so I don't know whether this is the right place):

d:\app\kuku\diag\clients\user_SYSTEM\host_3127173437_80\trace\sqlnet.log

***********************************************************************

Fatal NI connect error 12528, connecting to:
 (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=pc234)(Port=1521))(CONNECT_DATA=(SID=
orcl)(CID=(PROGRAM=D:\app\kuku\product\11.2.0\dbhome_1\perl\bin\perl.exe)(HOST=P
C234)(USER=SYSTEM))))

  VERSION INFORMATION:
        TNS for 64-bit Windows: Version 11.2.0.4.0 - Production
        Windows NT TCP/IP NT Protocol Adapter for 64-bit Windows: Version 11.2.0
.4.0 - Production
  Time: 14-JUN-2015 09:42:33
  Tracing not turned on.
  Tns error struct:
    ns main err code: 12564

TNS-12564: TNS: Verbindung verweigert
    ns secondary err code: 0
    nt main err code: 0
    nt secondary err code: 0
    nt OS err code: 0