INSTALLATION: Reporting Services extension error

Am installing reporting services extension but the below error keep rolling back at the end:
Occurred while adding users, domain\user, NT AUTHORITY\NETWORK SERVICE to the SQL Server Reporting Services DynamicsAXBrowser role in the folder DynamicsAX. The error is: The user or group name ‘domain\user’ is not recognized…
2014-08-14 09:10:51Z An error occurred during setup of Reporting Services extensions.
2014-08-14 09:10:51Z Reason: The user or group name ‘domain\user’ is not recognized.

Can you make sure if domain\user which you are trying to add present in the AD users list with proper permissions.