Problem: Clicking PrintFriendly button launches the browser print, not the PrintFriendly preview. 

Solution: Add the PrintFriendly JavaScript to your footer.php file.

• Go to your WordPress Admin Console
• Click Editor (under Appearance).
• Then click Footer (footer.php).
• Copy the code below and paste before </body>.

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<script type="text/javascript">
        // PrintFriendly
        var e = document.createElement('script'); e.type="text/javascript"; e.async = true; 
        e.src = '//cdn.printfriendly.com/printfriendly.js';
        document.getElementsByTagName('head')[0].appendChild(e);
​</script>