Why can't I record with back camera on Instagram?

I don't know if it's just my Iphone 5 or what but everything I try and record on Instagram with the back camera it closes and signs me out! I can't record perfectly fine with my Video recorder it is just the back camera! The only way I can record a video is through the front!

Does your phone have any problems? Did it drop recently? Mine works completely fine. Maybe it is just your phone.

I have the same problem on my iphone 5