I am running a Kubernetes 1.4 cluster on GCP Compute Engine(CentOS 7 machine). I've installed metric server and when I check metrics server pod logs,it's collecting log. However, kubectl top is failing with following error

kubectl top pods -n kube-system

Error from server (ServiceUnavailable): the server is currently unable to handle the request (get pods.metrics.k8s.io)

I've disabled firewalld and SELinux,still no luck.