The console or server log should give you some idea about what is wrong, the stacktrace is always available. I have doubts about the 'ID' attribute. I don't think it's available in oql.
Regards, Ruud
Dear Mertuza,
The OQL in Crash Course, please try this:
SELECT D/Name DepartmentName, COUNT(S/id) Number
FROM UserManager.Shift S
JOIN S/UserManager.Shift_PlanningPeriod/UserManager.PlanningPeriod/UserManager.PlanningPeriod_Department/UserManager.Department D
LEFT OUTER JOIN S/UserManager.Shift_Employee/UserManager.Employee E
WHERE E/ID = NULL
GROUP BY D/Name