If you right-click on the sub-report and select Format Subreport, there is an option on the Subreport tab called 'Suppress Blank Subreport'. This should suppress the sub-report but still calculate the values. Although I'm not sure that this option is in Version 8.5. I currently use version 10 and it's available in there and I assume it'll be in 11.5 too.
Also, you might want to put your subreport in it's own section and make it as small as possible, then it won't take up any space if there is nothing in it. If there is anything to print then the sub-report will grow (as long as you tick the 'Can Grow' option in the Common tab).
Kind Regards,
Jo.
p.s. I always add an extra suppressed section above the sub-report with a comment in (e.g. sub-report in section below), so next time I remember it's there
Edited by Joco - 20 Oct 2008 at 9:20am