WordPress MU

When i tried to use the domain map plugin it is not working.
I had given the ip and url.
But the mapping url is getting as
http://example.com/wordpress-mu/wordpress-mu/
and it shows Error 404 - Not Found

Please let me know what could be the reason.

Thanks

You have to have MU installed in the root.

Thanks andrea it is working now.
I have one more doubt
If i want to map a blog blog1.wpmu.example.com to http://www.example1.com what should I do.
I am new to the wpmu world thtz why am asking such a question.

Thanks

http://wpmututorials.com/plugins/donnchas-domain-mapping-plugin/

Or we now also offer a fully supported and rather more functional domain mapping plugin too.