According to its log, WSS complained it could not get trusted domains:
05/08/2008 10:09:18.72 Error when trying to get trusted forests and domains. Exception message: Access is denied. , callstack: at System.DirectoryServices.ActiveDirectory.Forest.GetTrustsHelper(String targetForestName) at System.DirectoryServices.ActiveDirectory.Forest.GetAllTrustRelationships() at Microsoft.SharePoint.Utilities.SPUserUtility.GetTrustedDomains(List`1 trustedForestNames, List`1 trustedDomainNames)
05/08/2008 10:09:18.72 Found 1 trusted forests ad.int.com.
05/08/2008 10:09:18.72 Found 0 trusted domains
05/08/2008 10:09:18.87 Error in searching user 'Bob' : System.DirectoryServices.DirectoryServicesCOMException (0x8007052E): Logon failure: unknown user name or bad password. at System.DirectoryServices.DirectoryEntry.Bind(Boolean throwIfFail) at System.DirectoryServices.DirectoryEntry.Bind() at System.DirectoryServices.DirectoryEntry.get_AdsObject() at System.DirectoryServices.DirectorySearcher.FindAll(Boolean findMoreThanOne) at System.DirectoryServices.DirectorySearcher.FindAll() at Microsoft.SharePoint.WebControls.PeopleEditor.SearchFromGC(SPActiveDirectoryDomain domain, String strFilter, String rgstrProp, Int32 nTimeout, Int32 nSizeLimit, SPUserCollection spUsers, ArrayList& rgResults) at Microsoft.SharePoint.Utilities.SPUserUtility.SearchAgainstAD(String input, SPActiveDirect...
05/08/2008 10:09:18.87* ...oryDomain domainController, SPPrincipalType scopes, SPUserCollection usersContainer, Int32 maxCount, String customQuery, String customFilter, TimeSpan searchTimeout, Boolean& reachMaxCount) at Microsoft.SharePoint.Utilities.SPActiveDirectoryPrincipalResolver.SearchPrincipals(String input, SPPrincipalType scopes, SPPrincipalSource sources, SPUserCollection usersContainer, Int32 maxCount, Boolean& reachMaxCount) at Microsoft.SharePoint.Utilities.SPUtility.SearchPrincipalFromResolvers(List`1 resolvers, String input, SPPrincipalType scopes, SPPrincipalSource sources, SPUserCollection usersContainer, Int32 maxCount, Boolean& reachMaxCount, Dictionary`2 usersDict).
But do I need care if the domain is "trusted" or not when only one domain exists? What I wanted was to get users from the same domain. MSDN also said "Users in the forest that the server is in (that is, a resource forest) are displayed automatically." But the reality was the opposite.
Finally, I had a try to add the WSS server's local domain using stsadm:
stsadm -o setproperty -url http://localhost:82
-pn "peoplepicker-searchadforests" -pv "domain:ad.int.com"
Although I had thought that the command should do nothing because I was not supposed to do that, ironically I could see users in the PeoplePicker control! :)