Some customers orders are not included in Reseller's invoice.
To be included in Reseller's billing order customer's order must have at least on provision item. For example, order without provision items can be created via API method CreateManualOrder_API. In case if all resellerls's customers orders have no provision items then no billing order is generated for reseller.
Also, customer order is added to Reseller's activity only when it is payed.
To bill reseller for orders without provisioning items it is suggested to create Debit Memo or billing order for required sum usign CreateManualOrder_API.