Virtual Private Server (Ubuntu)

Hello all.

I have purchased an ubuntu Virtual Private Server.

I have installed and configured apache 2 on the Virtual Private Server

I have also purchased a domain name, from a different company to my Virtual Private Server.

I have gone in to the "manage domain" settings and pointed the domain name to my Virtual Private Server's company "fasthosts" name servers. and set the ip address to my Virtual Private Server's IP address.

I have waited now for about 1 week

I can access my index.html page using the Virtual Private Servers IP address in the browser.

However,

I can not access my website's index.html page using my domain name.

I have used DNS look up and it says

"DNS No Valid Name Servers Responded"
"Not able to get a response from name servers within timeframe"

My question is, What else should i do ?

Because this is a Virtual Private Server do i need to create my own Name Server ???

Any help will be much appreciated.

Kind Regards

Simon