It is a SRM Classic scenario. ESA being used.
Shopping Cart created and the Purchase Order is created in the ECC side. However the related document tab is not updated and the Shopping Cart remains in incorrect status.
There is a Workflow in the ECC side that must be activated. This settings is a must in order to send the XML to SRM side to update the Shopping Cart. So the Related document tab and the status is updated as well. The KBA 1676004 explain in details how to activate this workflow in the ECC side.
The new Shopping Carts created will be updated accordingly. However the old documents will remain in outdated and with incorrect status, once the ECC will not send the XMLs to Purchase Orders created previously. In this case is required to perform the report Z_SC_STATUS_CHECK_3 available in the SAP note 729967.
Please check this link to further information about this issue. It is a link to SAP SRM Wiki page where you will find a central place with all information about SRM and its components, also some common issues.
SRM WIKI PAGE link
SRM Trouble Shooting Guide link