Hi Sylvain,

The custom reports in SmarterTrack will only use report items from existing reports.  At this time those reports will not breakdown to show what tickets are included in the numbers you get.  We do have a knowledge base article with instructions on how to create a custom report in SmarterTrack, that can be found here: https://portal.smartertools.com/kb/a2526/create-a-custom-report.aspx 

That said, you may be able to use the API to create a custom report outside of the SmarterTrack management interface.  You can access the API specific for the version of SmarterTrack you are running.  As the system administrator go to Settings and locate the Tools menu, this is usually at the very bottom of the menu.  You should see "API Documentation" as one of the options there.