Braille doesn't work in ubuntu

[Sauro Cesaretti]

Hello, 
I'm trying to use orca in ubuntu but
When I'm going to start live cd enabling accessibility support with screen
reader, the system starts in graphical mode
With orca and the speech support but even if 
I can read in my display that I'm in graphical mode and 
I can see that brltty is working correctly,
It'll not work in orca.
What can I do to use braille support with live-cd and during the
installation?
Thanks in advance

Best regards,
Sauro