Slave nodes fail to start, Error Log shows,

[04/08/13 18:22:49] [SSH] Opening SSH connection to <Slave Hostname>:22.
[04/08/13 18:22:53] [SSH] Authentication failed.
hudson.AbortException: Authentication failed.
at hudson.plugins.sshslaves.SSHLauncher.openConnection(SSHLauncher.java:907)
at hudson.plugins.sshslaves.SSHLauncher.launch(SSHLauncher.java:462)
at hudson.slaves.SlaveComputer$1.call(SlaveComputer.java:223)
at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
[04/08/13 18:22:53] [SSH] Connection closed.