I've already installed the iPrint client on the computer and when I try
to click on a printer to add it prompts me with "The selected printer
is not installed. Would you like to install it?". If I hit OK it
returns with the following error "iPrinter encountered a problem trying
to install the printer iPrint Printer - The printer is currently not
available". When I add the printer manually through the cups web
interface the iPrint listener responds correctly and prompts me for a
username and password and then successfully prints the document. So it
must be the browser plugin causing the problems

I have successfully added this printer with a computer running OS X
(10.3) and do not experience this problem with the plugin.

I've tried several different computers, restarting the browser, and
rebooting the machine. Any help would be appreciated.