I am a long time Webassist subscriber and I have this problem repeatedly! In this case when I click to update a form update the dialog box pops up for a second then disappears!
I removed the extension and re-installed it now I can't activate, had the same issue with ecart last week. Your activation server is reject the connection once again.
Please just send me the activation file I'm having to work on a laptop with an old installation because my development computer is not activated.