Passing a data from a subreport to an an array in the Main report

[crumpm]

CR 2008 - SQL database

I have a report that shows certain files, if they haven't had activity for a calculated period.

The {@Last Movement} is an array formula

maximum(makearray(file.last_time,file.last_bill,file.open_date))

which works fine.

I now have to add a new element to the array, by bringing in the maximum date from a subreport, which looks at certain transactions on the files, and produces a shared datevar - 1 per file.

However I have tried to use the shared variable , but I keep gtting the message " A summary has been specified on a non-recurring field. Details: @LastMovement"

I have inserted the subreport in Detail section A and the shared variable formaula in Detail B

Thanks
MC