Hi Ronna,
Thank you for purchasing the plugin.
I checked it on your site.

You are using some custom code to disable registration button on non registration page.

For example

http://group.ag2link.com/register/

On this page if you open the ajax modal using top register link, the submit button works but if you are any other page, It is disabled.

Please check your custom javascript and see if you have the event handler attached with registration submit button.

Thank you
Brajesh