Why deleting the thread? Enquiring on behalf of a client has some advantages - we the support team can better identify the shop you are talking about. Its a good question, we are glad to help you. One thing that's missing is the URL of the page where that happens, so that we could inspect it.
Most probably, though, the main script of Ecwid is missing on your site, that is the line of the following format:
is nowhere to be found in the source of your website pages' HTML code. If so, you may need to insert that line manually into the page or into one of the theme's template files.