Projections.RowCountInt64() returns 0 when i set SetFirstResult

SELECT TOP 3 id22_0_, Name22_0_, LastName22_0_, Descript4_22_0_, Phone22_0_, Mobile22_0_,
    Email7_22_0_, Email8_22_0_, AddDate22_0_, Country22_0_ FROM (SELECT ROW_NUMBER() OVER(ORDER
    BY __hibernate_sort_expr_0__) as row, query.id22_0_, query.Name22_0_, query.LastName22_0_,
    query.Descript4_22_0_, query.Phone22_0_, query.Mobile22_0_, query.Email7_22_0_,
    query.Email8_22_0_, query.AddDate22_0_, query.Country22_0_, query.__hibernate_sort_expr_0__
    FROM (SELECT this_.id as id22_0_, this_.Name as Name22_0_, this_.LastName as LastName22_0_,
    this_.Description as Descript4_22_0_, this_.Phone as Phone22_0_, this_.Mobile as
    Mobile22_0_, this_.Email1 as Email7_22_0_, this_.Email2 as Email8_22_0_, this_.AddDate as
    AddDate22_0_, this_.Country as Country22_0_, CURRENT_TIMESTAMP as __hibernate_sort_expr_0__
    FROM Customer this_) query ) page WHERE page.row > 3 ORDER BY __hibernate_sort_expr_0__

SELECT TOP 3 y0_ FROM (SELECT ROW_NUMBER() OVER(ORDER BY __hibernate_sort_expr_0__) as
row, query.y0_, query.__hibernate_sort_expr_0__ FROM (SELECT count(*) as y0_,
CURRENT_TIMESTAMP as __hibernate_sort_expr_0__ FROM Customer this_) query ) page WHERE
page.row > 3 ORDER BY __hibernate_sort_expr_0__

ISession session = NHibernateHttpModule.CurrentSession;

            var countCriteria = CriteriaTransformer.TransformToRowCount(query);
            rowCount = Convert.ToInt64(countCriteria.GetExecutableCriteria(session).UniqueResult());

            query.SetMaxResults(pageSize).SetFirstResult(pageIndex * pageSize);
            var customers = query.GetExecutableCriteria(session).List<Customer>();