Set Rest Pose - Character not responding properly

Hi All, 

Wondering if someone could please help?

I'm having issues with the 'Set rest pose' with my animation. Whenever I try to manoeuvre, my character is not responding properly i.e. when I move my head side to side my character doesn't respond and can become very erractic in movements. Also the red outline in the camera that's meant to cover your face keeps flickering in and out it never rests, it sometimes goes big then small, then nothing at all. 

Thank you,