Unable to find supplier site in Procurement. Getting error for supply items.

The supplier site isn't valid. It must be an active purchasing or sourcing-only site of the supplier and assigned to the requisitioning BU. If the same site name exists across multiple procurement business units, then either the requisitioning BU supplier site assignment must be unique, or there must be an agreement to determine the supplier and supplier site. A value is must for the Price attribute. For master items, you must provide a price when there's no list price defined for the item in Product Information Management or a different UOM other than the primary UOM of the item is provided.