failed to add node after install

Did a fresh install of the latest build on three ec2 instances.

Created a cluster of two nodes, did a few sets/gets.

Tried to add a new node, got back no error message, but it didn't show up in the UI.

Diagnostic logs show that it failed to add the node.

http://ec2-75-101-213-59.compute-1.amazonaws.com:8080/diag