Fail to add a node with the same IP with the "fail over" node in the cluster before

Created an attachment (id=390)
fail to add a node

Install northscale server 1.6.0beta2rc1-27 on 3 rhel 5.4 32bit boxes.
Add node B & C to node A to create a cluster of A, B & C.
Shutdown server at node C by uninstall northscale server. We can see it down on node A and node B.
http://screencast.com/t/ZDU1ZjAyMD
At node A, click Fail Over button of down server C
http://screencast.com/t/MDllYzY3OTM
Click rebalance button to rebalance the cluster of node A & B. Everything goes as expected.
http://screencast.com/t/OWNmOTQ5Z
Reinstall northscale server 1.6.0beta2rc1-27 on node C and it goes through initial setup.
http://screencast.com/t/OTY3ZjRhMDc
At node A of cluster A & B, click Add Server button to add node C to the cluster. Enter IP, username and password of node C and click Add.
First, the green ribbon does not appear and after few seconds, it appears as in the capture below.
http://screencast.com/t/NjFhNGE3
Click on Pending Balance button
http://screencast.com/t/M2E3ODdm
Click on Rebalance button, the page reloads almost rightaway without node C in the cluster
http://screencast.com/t/NjMwNWE5Zjkt
Nothing in pending balance.
Reload node C, I have to go through the initial setup again.