Hi Natalia,
As mentioned in my previous reply WIP quantity document is created when you calculate WIP at Target Costs (please check your Result Analysis Key settings) and used to revalue WIP at actual costs in ML.
The purpose of this document is to identify quantities of materials/activities issued in respective which constitute WIP. Later on in ML those quantities are revalued with actua prices for respective periods.
In order to calculate WIP at Target Costs you need Target Cost Estimate. This target cost estimate is calculated based on quantity structure BOM/routing assigned to your production/process order or Product Cost Collector.
You can't assign quantity structure to CO Production Order and because of that you can't calculate Target Cost Estimate. As a result you don't get WIP quantity document and can't revalue WIP in ML.
Regards,
Szymon