Love this plugin which I got to work on a test site but can't make it work for a client site.
In both cases I am using WP 3.9 and the Vantage theme.
Could it be…?
1. The test site is on Bluehost.
2. The client site is on GoDaddy.
On the client site I don't get the modal html output from your script. Do you require a certain version of PHP?
And the plugins are similar but not identical. Do you know if your plugin has issues working with other plugins?
I suppose I could to a test site on GoDaddy but I don't want to do that.
BTW -- you have broken links to your site to pay for your plugin upgrade. I think they were in the plugin admin.