I guess that will depend. I'm not familiar with Retica or how it works. Does it post straight to the cloud? You didn't receive any notice or warning that your SD was full before or while taking the pics? If the answer to both questions is "No" then it sounds like it may save pics to an in app folder which is likely on your internal memory. Since I haven't heard of a recovery app that works, you may be able to find them with a file manager app such as Astro or ES Explorer, and just locate search for the pics. Which doesn't explain why you aren't able to find or view them now... If you feel they are there and may have been deleted or something, which it kind of sounds like since your are trying recovery software, you might want to try Recuva on your PC. Connect your device, unlock and open it, make sure you can see it in your list of drives under My Computer, and direct Recuva there. If they are there and recoverable it should find them.
As for why you can't find them naturally... I'm not sure. I can't imagine that the app would say it was taking the pics and not take them, or not give you a warning that your memory was full. Maybe you have more detail that you haven't given yet.