Here are the steps to change your BI Publisher Enterprise Server to be in a debug mode:

1. Login to BIP as Administrator
2. Select Admin -> System Maintenance -> Server Configuration
3. Change Debug Level to ‘Debug’ under General Properties

   
   

4. Click on the ‘Apply’ button and restart the server.

Now you should start seeing more information than when the ‘Debug Level’ is set to ‘Exception’ in the application log file.

Source: http://bipconsulting.blogspot.com/2010/01/bi-publisher-logging-debugging-part-3.html