Look at the link I supplied then try installing using the Linux tools. In the Kubuntu menus, there is a utility for setting up printers. Or just enter "localhost:631" into a browser.
When you refer to the Brother CD, I assume it is the disk that came with the computer. I think what has happened is that Linux just mounted the disk and put an icon on the desktop. That does not install the printer.
Normally, the disk that comes with a printer will have drivers only for Windows and Mac, but this may start changing soon. Meanwhile, use the Linux tools.