Not working

Following the thread for installing / re-installing Form Toolkit / Form Builder I am stuck again. After applying CAPTCHA I try to insert the Server validation for it.
All I get is a blank window (screenshots). After closing it there is another popup error.
I am spending more time with installing / uninstalling / reinstalling DA extensions than getting a simple form work. I will return this unfinished extension until it is working.
This is enough now. I want my money back.

I un-installed it, and now I get a pop-up message each time I open Dreamweaver "Unable to open script file ..."

What has to be done, to get rid of this experimental extension, so that Dreamweaver and all the other extensions are working properly again??? The error message looks into a folder Shared\WebAssist\WAFormToolkit\WA_Configuration.js.

I uninstalled it and deleted the Cache file