Follow-up
I experienced a combination of 2 problems:
1, Ecart's wizard "onMouseUp" error - fixed by the new version of pages.js
2, Protx's testing server upgrade which no longer supports Ecart's protocol 2.22
For a first e-shopping project this combination left me very confused/fustrated!
However, I can confirm that Ecart's wizard will work and efficiently generate code to link with Protx, so long as a full Protx account has been arranged, and not simply the Protx testing server.
Hope this helps!