Can't stop spam comments

Hello,

Seems each day I’m getting 100’s of comments posted – most from “someone@domain.com” – that have links to other sites usually selling something that is relevant to the category it’s posted in.

I don’t what I’m doing wrong – I added a Captcha….and, when I go to my site, and click on an article, and try to leave a comment I have to Register, and enter the Captcha word…….

Can anyone tell me how these comments are getting posted on my site?

The site is:
http://www.technologysolutionslive.com

Thanks!
Rob