It looks like a few things may be happening.
1) Are you sure you installed the "Database And Server Behaviors" extension from the Adobe store? Can you access the Server Behaviors panel?
2) It looks like the installation didn't complete properly. After you install with the extension manager, the next time you open dreamweaver and open any page it should initiate a secondary installer that adds more files including the one referenced in your error. I think you may need to reinstall ecart and make sure the secondary installer runs after you have verified that the database and server behaviors extension has been added.