EC2 slaves not connecting

Node jenkins-aws-centos-6.5-64-LinuxBuildOrTest-v1.4 (i-70f6ea9c)(i-70f6ea9c) is ready
Connecting to ec2-54-159-86-48.compute-1.amazonaws.com on port 22, with timeout 10000.
Connected via SSH.
bootstrap()
Getting keypair...
Using key: --------
Authenticating as -------
take over connection
Creating tmp directory () if it does not exist
mkdir: missing operand
Try `mkdir --help' for more information.
Verifying that java exists
java full version "1.7.0_51-b13"
Copying slave.jar
Launching slave agent: java  -jar /slave.jar
ERROR: unexpected stream termination
java.io.EOFException: unexpected stream termination
	at hudson.remoting.ChannelBuilder.negotiate(ChannelBuilder.java:331)
	at hudson.remoting.ChannelBuilder.build(ChannelBuilder.java:280)
	at hudson.slaves.SlaveComputer.setChannel(SlaveComputer.java:365)
	at hudson.plugins.ec2.ssh.EC2UnixLauncher.launch(EC2UnixLauncher.java:172)
	at hudson.plugins.ec2.EC2ComputerLauncher.launch(EC2ComputerLauncher.java:107)
	at hudson.slaves.SlaveComputer$1.call(SlaveComputer.java:241)
	at jenkins.util.ContextResettingExecutorService$2.call(ContextResettingExecutorService.java:46)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:744)