in the sub report for the shared variable formula that gets your amount set it to use default values for nulls. i think that will address the 0 issue, other wise you can reset the value in the main report by placing another shared variable in the another group header (above the sub report) to set the shared variable to 0.
to gtrid of the space you can
suppress every section inside of the sub report
in the main reoport right click on the sub report ans select format subreport
select subreport tab
make 'suppress blank subreport' as true (checked)
then in the main report section expert set the section the subreport is on (GH) to 'suppress blank section' as true
Edited by DBlank - 02 May 2012 at 3:36am