I imagine you are using the 'hide (drill down OK)' setting?  If so, that is just how it works.  To get the result you want, your best bet is likely to create a parameter called "report type" or something similar with the values being 'summary' and 'detail'.  You can use this run-time option to conditionally supress sections based on the report type.  It won't be as nice as being able to double click on a section to see the rest of it, but depending on the version of Crystal you are using, you can switch back and forth easily without losing any other parameter settings you might have.  In v2008, you can even change parameter settings while viewing the report from a side panel.