Find out, who can create shifts and more importantly for whom this permission is applicable.
Shifts can be created by admins and managers. Admins can create shifts for all locations & departments, whereas managers can only create shifts for locations & departments which the manager is assigned to him/herself.
Managers can only create shifts, if the admin has given them the permission to do so. The permissions are managed in the employee profile under the tab "permissions". Here the admin can determine whether the manager can create, change or delete a shift.
Employees are not able to create any shifts, they can only apply for shifts.