People Picket cannot find user

Hi

I am using SharePoint 2010. I have a problem on people picker cannot find user in AD01.

The AD01 domain has a 1-way trust.

AD01's users are able to access SharePoint site, User Profile Sync was successfully run on AD01 to SharePoint User Information List. Telnet and Ping AD01 have no problem.

I had run the people picker stsadm script but still cannot find any user is AD01.

Hope someone here can assist me.

Thanks!