Hi,
No. You don't need ScriptManager. The problem is mostly due to our JavaScript files failed to render, which usually occurs when the website requires login but you try to access the page it with anonymous user (without login).
Our product uses a separate file eo_web.ashx to render JavaScript. So if you put the dialog on PageA.aspx, PageA.aspx will call eo_web.ashx to request the JavaScript code. Thus you will want to check whether file eo_web.ashx is indeed on your application's root directory. If the file does exist, then you can check the permission. Even though PageA.aspx is accessible to anomyous user, it won't have the JavaScript code it needed if eo_web.ashx is not accessible to anonymous user.
If the file does not exist, you can simply copy it over from the installation folder. If the file does exist, try to modify your web.config to allow anonymous access to eo_web.ashx. You can find more information about this at here:
http://www.essentialobjects.com/Forum/Default.aspx?g=posts&t=1401Please let us know if this solves the issue.
Thanks!