Lab 3 Fails with invalid reference format

Hi,

I keep getting "Invalid reference" when I use Lab 3 exercise and do this on my docker CLI

 docker container run -d --name=k8s -p 8080:8080 gcr.io/google_containers/etcd:3.1.10​etcd --data-dir /var/lib/data

I think the image gcr.io/google_containers/etcd:3.1.10​etcd does not exist. As a result everything else will fail in this lab. 

Can someone help please?