Help setting DNS for new site

Hi, I have a multisite WP installation up and running. I have successfully configured one domain to work successfully with my server. I am now in the process of setting up another domain but I have run into problems. I will explain what steps I have taken:

1. I have set up a new site on my multisite installation. I have populated it with a theme and content. Before switching the primary domain it was visible in my control panel
2. I configured the A records to point at my server’s IP address
3. Using Domain Mapping, I set the primary domain

After these steps, I went to try the domain in the browser but it didn’t work. Chrome returned the following error:

Error 105 (net::ERR_NAME_NOT_RESOLVED): Unable to resolve the server's DNS address.

Any ideas? Is there a necessary step that I have not carried out?

Thanks