Your answer didn’t make sense – I reported that neither redirect to a new browser window nor opening a lightbox worked. This would have been a fatal flaw in your non-paid version since anyone trying to print a dynamic page, like the one I needed help with in this post, could never be printed using your plugin.
I discovered the reason it is working on my other site is because it has the WordPress Jetpack installed. So, when I installed Jetpack on the site with the problem, your plugin is now working properly.