Site won't load with "www." at beginning of domain name

[leadthepack]

I'm setting up a site on SquareSpace with a custom domain on DirectAdmin. The site works when you go to jezrocmetalworks.com, but not when you go to www.jezrocmetalworks.com. I've triple-checked the settings required by SquareSpace and filed a support ticket with them, but they just said that, according to my screenshot of the DNS settings, everything looked fine and I'd have to contact the company in charge of my domain.

Any ideas why the site will work without "www." at the beginning, but not with?

 

[nobaloney]

In my testing the site with www redircts to the same sitename without www. Then they may or not load, and sometimes take a long time or timeout.

Jeff