Strange problem with adding some users

Question

I'm encountering problems adding "some" users(of a certain domain) to a group..

The code works every "domain1" user, but for "domain2" for doesn't:

 Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(delegate()
            {
                using (SPSite scSite = new SPSite(fullsite))
                {

                    using (SPWeb scWeb = scSite.OpenWeb())
                    {
                        scWeb.AllowUnsafeUpdates = true;
                        scSite.AllowUnsafeUpdates = true;

                        SPGroup gruppo = scWeb.SiteGroups[groupName];   //FIND
                        SPUser utente = scWeb.EnsureUser(username);    //FIND
                        gruppo.AddUser(utente); 
                        gruppo.Update();
                         }
                     }
            });

Exception is:

You do not have permission to perform this action or access this resource.   at Microsoft.SharePoint.SPGlobal.HandleComException(COMException comEx)
at Microsoft.SharePoint.Library.SPRequest.UpdateMembers(String bstrUrl, UInt32 dwObjectType, String bstrObjId, Guid& pguidScopeId, Int32 lGroupID, Int32 lGroupOwnerId, Object& pvarArrayAdd, Object& pvarArrayAddIds, Object& pvarArrayLoginsRemove, Object& pvarArrayIdsRemove, Boolean bRemoveFromCurrentScopeOnly, Boolean bSendEmail)
at Microsoft.SharePoint.SPUserCollection.UpdateMembers(Object objUpdateInfo, Object objAddIds, Object objRemoveLogins, Object objRemoveIds, Boolean fSendEmail)
at Microsoft.SharePoint.SPUserCollection.AddCollection(SPUserInfo[] addUsersInfo, IEnumerable`1 addUsers)
at Microsoft.SharePoint.SPUserCollection.Add(String loginName, String email, String name, String notes)
at Microsoft.SharePoint.SPGroup.AddUser(SPUser user)

If I manually add the users, everything goes fine..

Context info: that code runs on a Web Service. I also tryed to run it as Console App and Web Part.. But with no changes on the behavior.

The problem I'm facing is probably caused by the 2 domain the machine is trusted with: with 1 domain I have no problem, with the other system fails to add users to group by code but with people picker everithing goes fine..

I begin to think I have a problem with privilegs on AD or something like that.. Any suggestion?

Thank you very much!

Answer 1

Ok, the problem was really simple:

The trust between AD was not bidirectional but one way only.

When the trust becomes bidirectional the problem solves automatically!