How to get DFC trace: (on APP SERVER MACHINE)

The "dfc.properties" file to use would be the one that Webtop uses. This should be found in the <webapp deployment directory>/webtop/WEB-INF/classes folder.  For instance if you were using tomcat on windows you might find the file in the following location
<webtop_home>\WEB-INF\classes.  

Can you try the following settings in your dfc.properties for capturing the DFC trace

dfc.tracing.enable=true
dfc.tracing.include_rpcs=true
dfc.tracing.verbose=true
dfc.tracing.mode=standard
dfc.tracing.log.level = DEBUG
dfc.tracing.timing_style=date
dfc.tracing.date_column_width=12
dfc.tracing.date_format=yyyy-MM-dd hh:mm:ss.SSS
dfc.tracing.max_stack_depth=10
dfc.tracing.include_session_id=true
dfc.tracing.dir=${user.dir}/documentum/logs/

and then send us on the resultant trace file from <$TOMCAT_HOME>\documentum\logs.

You can reset dfc.tracing.enable=false when you have captured the trace