Domain Mapping not working

The subdomain I am trying to map to is http://allegrini.yachtblogs.com/. If you visit it right now, it works fine. The domain I am trying to map from is http://allegrini.co.uk/. I temporarily removed http://allegrini.co.uk/ from the "Custom Domain" in the tools > Domain Mapping plugin field because I can't get anything to work.

1. When I add http://allegrini.co.uk/ to the custom domain field, the plugin appears to work properly because when I visit http://allegrini.yachtblogs.com/ I am forwarded to http://allegrini.co.uk/. However, for some reason nothing exists at http://allegrini.co.uk/. I added the A record as directed by the plugin usage to the proper static IP address and I've confirmed that this is the correct address. I edited the A record about 24 hours ago.

Any thoughts on why http://allegrini.co.uk/ isn't coming up with my site?

Thank you.