E:Malformed line 47 in source list /etc/apt/sources.list (dist parse), E:The list of sources could not be read

Binary package hint: update-manager

I was having problems with installing repositories. Somebody told me that I should only put karmic in the end while putting new mirrors in the source list.
Here is the link:
http://ubuntuforums.org/showthread.php?t=1308888

like this:
deb http://cz.archive.ubuntu.com/ubuntu karmic

But after that, I got this bug:

Could not initialize the package information
An unresolvable problem occurred while initializing the package information.
Please report this bug against the 'update-manager' package and include the following error message:
'E:Malformed line 47 in source list /etc/apt/sources.list (dist parse), E:The list of sources could not be read.'

Now there is a Red icon near volume control and when I click on it, it asks me to report the above bug.

I hope, somebody here will help me.

Thanks

P.S I'm using Ubuntu 9.10 Karmic Koala