Why can't I take a screenshot of a snapchat?

[AC Question]

I have an LG Lucid 2 smartphone, and to take screenshots, I hold the power and volume down keys. This usually works fine, such as when snapchat isn't open, or even when the app is open but I'm not actually viewing a snapchat. But, for some reason, once I actually open a timed image someone else sent me, the screenshot function just seems to have been completely disabled, and I have no idea why. I hold my finger to the screen to view the chat, and before the timer runs out, I try to hit the volume down and power buttons, and even when I'm holding them for the entire duration of the image(approx. 10 sec), it just doesn't take a screenshot. In fact nothing happens. At all. Why is that?

 

[Javier P]

I think the main point of snapchat is avoiding that kind of saving pictures.

You can take a look here anyway.

http://forums.androidcentral.com/t-mobile-htc-one/351059-how-do-you-screenshot-snapchat.html