Help Problems with camera :(

[Lensy]

I have one problem. I have Samsung Galaxy Tab 3 Lite and camera is working perfect. But I downloaded one app that I really need, and that app needs camera, but camera is not working when I need it. It's not that black screen crash, I can see text and everything, but it's like someone is holding finger on my camera. I all ready had this problem on my old tablet, when I downloaded CandyCamera and app said that something is wrong with my camera, but all other apps with camera were working.

Please help if you can.
Thanks.

Lensy