If you followed all setting up instructation and Peoplesoft "PeopleBook", or maybe their technical support note, you still get the problem to enable "PeopleCode Debugging" function -
Check your debugging port number -
The default port number is 9500. If this port number 9500 got used by an other application, you need to change the port number to a new one - which you are sure it has not been used by any application.
It will work - good luck!