People picker not able to fetch one user

Hi,

I am trying to fetch user in people picker .However ,it is not fetching one of the user in people picker in my test site.When I am trying to get the same user in my production site , iam able to find the user there.The above is occuring for the whole test farm on every single web application.

I tried following.

1. Turned off firewall on test.(not worked)

2. Checked the user in server manager -- > user groups(user is present there)  (IN TEST SERVER)

Any Clues?