Are you using dark / shiny material? That can confuse it.
Also if too much light is shining into the machine – try covering it with a towel or something.
Otherwise I’d try the stuff in this post:
Are you using dark / shiny material? That can confuse it.
Also if too much light is shining into the machine – try covering it with a towel or something.
Otherwise I’d try the stuff in this post: