"Add item " not working for External catalogs when shopping cart is changed

Hi All

I am having a queer issue with External catalog shopping carts.

Whenever I try to change a shopping cart during approval or after having it sent back by the approver & click on Add items  the items are not transferred from the external catalog.

However when I create the shopping cart initially ( before approval) , I can go back & forth as many times as required & add items again and again. In this case  Add items takes me to a new screen with all the options like Old shopping carts, External catalogs etc.

In the former case, it provides a drop down , next to add items and doesn't transfer the catalog items.

We are using SRM 7.0 in classic scenario & using OCI HTML punch-out

Also we are using Standard One step Approval workflow , ( approval with completion)

Thanks

Kedar