Check your Apple ID is in your user ID in System Preferences>User (Unlock)>Apple ID - Change.
Try deleting your Apple ID and re-inputting it if it is there.
Do this on all the shared Macs and re-boot them.
Also check Sharing in System Preferences (on the shared Mac/s) and click Remote Management (on) and click all the options (on) in 'Options' under Remote Management.