Spark ec2 lunch problem

[Garry Chen]

Hi All,
                I am trying to lunch a spark ec2 cluster by running  spark-ec2 
--key-pair=key --identity-file=my.pem --vpc-id=myvpc --subnet-id=subnet-011 
--spark-version=1.4.1 launch spark-cluster but getting following message 
endless.  Please help.


Warning: SSH connection error. (This could be temporary.)
Host:
SSH return code: 255
SSH output: ssh: Could not resolve hostname : Name or service not known