LinQ Issue

var leads = (from lead in svcContext.LeadSet
                                 join ma in svcContext.CreateQuery("new_marketingactivity") on lead.Subject equals ma["new_name"]
                                 join sub in
                                     (from mai in svcContext.CreateQuery("new_marketingactivityinstance")
                                      join ma2 in svcContext.CreateQuery("new_marketingactivity") on mai["new_marketingactivityid"] equals ma2["new_marketingactivityid"]
                                      select new { _lead = mai["new_marketingactivitiesid"], _ma = ma2["new_name"] }) on lead.LeadId equals sub._lead
                                 where (!lead.Subject.Contains((string)sub._ma))
                                 orderby lead.EMailAddress1
                                 select new Lead
                                 {
                                     LeadId = lead.LeadId,
                                     OverriddenCreatedOn = lead.CreatedOn,
                                     Subject = lead.Subject,
                                     EMailAddress1 = lead.EMailAddress1
                                 });