Sniply uses iframe technology to load web pages. Sites with high security settings sometimes block iframes for security purposes. For example, banking portals and payment processing sites like PayPal are not supported by Sniply.
Don't worry though, Sniply does support over 99% of all sites on the internet. There's not much we can do about the remaining 1%, since only their webmaster can alter the security settings to support the technology we use.
However, if you own the site that is experiencing this issue, there is a simple solution that just requires you to put a line of code on your website. This will optimize your site for Sniply (and your frame breaker will still work perfectly) and fix any user experience issues. To get started just go to "Account" -> "Embed on Website/Blog" on your dashboard and follow the instructions to add the code to your website. A full explanation of how this solution works can be found here.