I just had a look at your link, and I am certainly getting an error back from Silverstripe on the URL.
When you installed Silverstripe, did the installation process complete correctly? It almost looks like you have a DB connection issue, but I cant get any further information out of the system from here.
What my be worthwhile to do, is to try to connect to silverstripe on the development URL, and pass a "?isDev=1" to silverstripe to see what additional information you get out of the error.
Finally, it may be useful to know what OS, DB and webserver combination you are running.
Looking at it in ?isDev=1 mode - looks like you are running the site in Live mode but your database hasn't been setup correctly. You could try putting the site into dev mode (by adding Director::set_environment_type("dev") in your mysite/_config.php file) and then trying to run dev/build again.