Kubernetes doesn't pull from private Docker Registry
In most cases where I've come across this issue, it is almost always your credential secret being incorrect. The proper format should be along the lines of
apiVersion: v1kind: Secretmetadata: name: registrypullsecretdata: .dockerconfigjson: {BASE64 encoding of your config}type: kubernetes.io/dockerconfigjsonFrom memory, the type field has changed in recent versions of k8s so definitely check that you have the correct type listed.
Also, your yaml example has bad indenting, but thats likely a SO editor issue.