Screen Sharing not working for non-admin local accounts on Yosemite Server Question says it all. Current versions of Yosemite (10.10.3) and Server (4.1).

Under Server > Settings
     Enable screen sharing and remote management checked.

Under Server > Access
     Admin and a non-admin local user listed.

I can log in Screen Sharing as the Admin user but not via non-admin accounts.
Be sure to add the non-admin user/group (depending on if multiple users) to the Remote Management section of Sharing in System Preferences to allow access.

(Thanks Guy!)