Hi,
Please be more specific about the two forests. For example, do they have one-way or two-way trust?
By default, People Picker will only return users, groups, and claims from the domain on which SharePoint Server 2010 is installed. If you want People Picker to return query results
from more than one forest or domain, you must either have a two-way trust between the forests or domains, or you must configure People Picker to use an encrypted account and password for a one-way trust between forests and domains. For more information about
trusts, see Managing Trusts
(http://go.microsoft.com/fwlink/?LinkId=207573).
For more information about people picker in multiple forests, check out the following article:
People Picker overview (SharePoint Server 2010)
http://technet.microsoft.com/en-us/library/gg602068.aspx
Thanks,
Rock Wang
Regards, Rock Wang Microsoft Online Community Support
