没有得到http请求自定义标头

Question

I am setting http headers in angular js interceptor to make a http request but on php end not getting header.

   var key = sessionStorage.getItem('user_type');
            //for app version
            config.headers['AppVersion'] = '1.0';
            config.headers['language'] = web_language;
            if(key == null)
            {
                if(localStorage.getItem('user_type'))
                {
                    config.headers['user_type'] = localStorage.getItem('user_type');
                }
                else
                {
                    config.headers['user_type'] = '';   
                }
            }
            else 
            {
                config.headers['user_type'] = key;
            }
            return config;

In browser in network tab in headers i can see the user_type value sent in request.

In php I am using codeigniter:-

$user_type = $this->input->get_request_header('user_type');

I want to fetch user_type header in php end but not getting. I am using the linux redhat server godaddy hosting.