Hi Kiran,
The jenkins is not able to remotely execute the ansible command. The installation field in the global configuration must contain the path of the directory where the ansible binaries are installed. Note that in the last release of the plugin this configuration is not required anymore when ansible is available in the PATH environment variable.
There are two possible solutions: either you install ansible on your Jenkins server or you setup your Ansible server as a Jenkins slave.
Hope this helps.
--
Jean-Christophe