hence we have installed the agent for individual workstations from normal installation wizard and it was successfully scanned; and although we have followed the exact steps as provided in 

https://www.manageengine.com/products/service-desk/help/adminguide/configurations/discovery/methods-of-deployment.html

the pushing is not happening through group policy.

 

Note: 

We are using the Manage Engine Service Desk Plus 9.3 Build 9307 and most of our workstations have the agent with older version

Have anyone faced such issue? and Is there any special configurations in the group policy or pre-requisites in the network to make pushing happened successfully?