I have a problem with reserves. I have configured items to be reserved, trying to set them up as reserve= optional or always. 

I have tested the issue with items with reorder policy = order or lote-by lot. I have encountered the same problem. 

When I'm using planning worksheet and receive a supply proposal, the system reserves quantities by itself when it's necessary. 

If I delete reservations and try to do the reservation again manually I get this message:

"You cannot reserve this entry because it is not a true demand or supply"

I get this message allways I'm trying to reserve manually from planning worksheet.