Я использую базу данных Access и пытаюсь загрузить объект DataTable, но получаю сообщение об ошибке. Мой запрос вызывает публичную функцию CountWeekDays в стандартном модуле доступа, и при запуске через сам Access возвращает правильные результаты просто отлично. Почему это не работает при вызове через приложение .NET?

 SELECT tbl1.ProjectID, tbl1.EntryDate AS StartDate, tbl2.EntryDate AS EndDate, 
(SELECT (ChecklistDayMax - ChecklistDayMin + 1) AS DaysAlotted FROM milestone_def WHERE MilestoneDefID = [@milestoneID]) AS DaysAlotted, 
(SELECT ProjectPriority FROM project_master WHERE ProjectID = tbl1.ProjectID) AS Priority,    
 IIF(Priority = 1, (SELECT BonusDaysFH FROM milestone_def WHERE MilestoneDefID = [@milestoneID]), 
 IIF(Priority = 2, (SELECT BonusDaysFM FROM milestone_def WHERE MilestoneDefID = [@milestoneID]), 
 IIF(Priority = 3, (SELECT BonusDaysFL FROM milestone_def WHERE MilestoneDefID = [@milestoneID])))) AS BonusDaysAllotted, 
 CountWeekDays(tbl1.EntryDate, tbl2.EntryDate) AS DaysRequired
 FROM checklist_entries AS tbl1 
 INNER JOIN checklist_entries AS tbl2 ON tbl1.ProjectID = tbl2.ProjectID
 WHERE tbl1.ChecklistDay = (SELECT ChecklistDayMin FROM milestone_def WHERE MilestoneDefID = [@milestoneID])
 AND tbl2.ChecklistDay = (SELECT ChecklistDayMax FROM milestone_def WHERE MileStoneDefID = [@milestoneID]);