On Ubuntu 2012.04 I open "Connect to Hidden Wireless Network", type the network name, click connect. After a minute the dialog below appears:
I can only cancel... not very helpful.
Why does the dialog not just offer me to type the password?
On Ubuntu 2011.04 I am asked for a password and it just works...
The network is WPA2 Personal, but this other issue means I have to select "None" for security.