iMessage Screen Sharing greyed out

[Blackstick]

Hi Folks,

Is anyone on Yosemite able to use iMessage Screen Sharing between two accounts (both are on Yosemite). The icon is greyed out on both machines-- yet the screenshot below indicates it's certainly possible - but mine has the Screen Share icon greyed out - maybe Apple hasn't enabled it?

 

[gasbi]

I have the same problem. Did you found a solution??
Certainly, I used it before, but I don't know why now it isn't working.