change the warning dialog (suggestion)

1. I think this warning You cannot create appointment for this location is not informative enough. Maybe we could add You cannot create appointment for this location. Ensure there is at least one Worker with this location?
2. Also suggestion: now, if there is no worker with any chosen location and i'm trying to add appointment; I cannot because there is no worker who can conduct the appointment (I see warning displayed). But I can choose from the location list all available locations eventhough there is no worker available. Maybe in such case, there shouldn't be displayed any locations at all during adding appointment?