Having the same error
I'm having the identical error message at the top of this thread:
When trying to add an AddToCart button. I've tried uninstalling and reinstalling the extension. The extension manager seemed to hang up. So I resorted to completely remove Dreamweaver. Reinstall, and then reinstall all my extensions. Still get the same error. Now I went and opened up an older site detail page, for which this site is based upon, and that page I can re-open the Add to Cart dialog without incidence. So, I'm wondering if there's something on page that is causing the issue?
I've attached a Zipped version of the page.