Has anyone successfully implemented Business Function LOG_MM_SSP_1 and been able to bring back shopping carts from External Punchout Catalogues?

EHP 6.0 allowed us to implement the Self-Service Procurement in the browser from Internal and External Catalogues. Although we can access and create shopping carts  the External Catalogues we are unable to bring back the Shopping Cart. Has anyone successfully implement this aspect of SSP and overcome similar issues?

Regards

Ant