The error message is enough for telling the main reason that caused this trouble for you. This is a denial report for you request. You wanted to view the details for your website, which is denied by the server. You can go to your hosting providers Control Panel and look for settings for viewing the application errors. Or just set this,
<configuration>
<system.web>
<!-- Set the customErrors to be viewed on the remote connections. -->
<customerrors mode="RemoteOnly" />
</system.web>
</configuration>
This would let you see the errors on the remote connections. You can furthermore ask such questions on
Offical IIS Forums.