If you use multiple forest, you need same command for People Picker:
try this:
(
http://nuke.sharepointinside.it/Blog/tabid/57/EntryID/6/language/it-IT/Default.aspx)
PART I : Farm
on each front-end and on all server that host Central Administration, this store a password in the DB for crypt the password of the next command
stsadm –o setapppassword–password <SomeKey>
PART 2 : Web Application
For each web application you need to use People Picker:
stsadm -o setproperty -url http://<server:port> -pn peoplepicker-searchadforests -pv "forest:forest1.net;forest:forest2.net,<domain\user>,<password>;domain:domain.forest1.net,<domain\user>,<password>"
Rif: http://technet.microsoft.com/en-us/library/cc263460.aspx
Regards,
Francesco
www.sharepointinside.it