How to exclude closed Item Lines on a Purchase Order Report?

Hi

Where a supplier is unable to fulfil part of a purchase order we have been using the recommendation from the help files and marking that particular line as closed on the purchase order rather than deleting it, this way we keep a record of what was ordered.

I have a report written over open purchase orders to show the outstanding open quantity, however items closed as per above still appear as open items. I cannot find a way to filter these out of the report - anybody got any ideas?

Thanks

Sandra