how to get Orca to speak in lightdm

[Milton]

Hello List,

I use Ubuntu Trusty with Orca 3.14.3 in Unity. I thought to show some 
friends the Lubuntu desktop and install this with the help of the 
software centre. But after this I have no Orca in the login screen. I 
did in a terminal:
sudo dpkg-reconfigure lightdm
without success.
can you tell me how to get Orca to speak again in the login screen? 
Thank you.
Milton