Host not found error while executing copy module

[Diwaakartg Ganesh]

Ansible version :1.9.4, 1.9.3, 1.9.1,

Using ec2, so specifying pem key in ansible. Cfg

I have used ansible for while,  but this error is strange. 

Copy module works fine when executing in ad-hoc like the snippet below. 

The below line is just an example. 

    Ansible instance123 -m copy - a "src= dest= mode =" 

But gives "host not found" while executing the same module in playbook. 

I checked command module both in playbooks and trying it in ad-hoc also. That works fine. 

I found that version 1.8.2 had this error,  and I tried all state versions of 1.9

I find this strange, any help appreciated.