How come adding a new search head to my cluster is causing other search heads' statuses to change to PENDING?

[vrmandadi]

I have three search heads(7.1.1) in a clustered environment, and I am trying to add a new member in the cluster.I followed the document provided by Splunk, and I followed the same steps. But, when I add the new search head, all the other search heads go to pending state.

Below are the steps I followed.

1. Installed Splunk (same version as other search heads)
2. Initialize
3. Add instance

https://docs.splunk.com/Documentation/Splunk/7.2.0/DistSearch/Addaclustermember

Thanks,
Vineeth