Source of supply deleted when changing plant in SC

Hello everybody,

I've found an strange SRM 7 behaviour. When I'm creating a shopping cart and I assign a valid supplier for an item (Source of supply/ Service Agents tab) : why is it unassigning the supplier every time I change the Location/plant at "Item data" tab?

How can I avoid this ? Is it a standard behaviour?

I have noticed that method UPDATE_ITEM_INTERNAL from /SAPSRM/CL_PDO_BO_SC class, produces a SOS_VALIDATION where the supplier is marked as deleted (del_ind  = 'X').

Thanks.