DNS not working for domain map site

I have installed and domain mapping, and got it working fine for the first domain no problem.

For the second domain I have set the same IP address DNS record change, but the URL now goes here, some kind of weird internal server error:

http://digital-government.info/

Also the domain mapping won't pick it up.

The DNS entry is exactly the same as the one that works, any idea what I've done wrong then?

thanks, Neil.