On a Sage CRM 7.3 system integrated with Sage 200, a user can not add a new line item to a Web Quote or Order.
When a user tries to add a new line item to a new quote / order the "Save" button in the new line item box does nothing.
This issue has been resolved in Sage CRM 7.3a
This is an issue in Sage CRM 7.3 GA.
The button "Save and New" works as expected in the new line item box.