Upgraded to Yosemite and can no longer remote into my work iMac through screen sharing- it is turned on in settings?

My screen sharing functionality did not show up in the dock with an updated icon. It had a question mark- shows my connections but nothing works, I did make sure screen sharing is on and also connected to VPN. Once I tried to launch screen sharing nothing happens. Such an elegant solution in Mavericks not does not work. Ugh. Help!