web.config ignores customerrors="on" attribute

Hi I've got a site where I get the classic:

Server Error in '/' Application.

Runtime Error

Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.

<!-- Web.Config Configuration File -->

<configuration>
    <system.web>
        <customErrors mode="Off"/>
    </system.web>
</configuration>

<!-- Web.Config Configuration File -->

<configuration>
    <system.web>
        <customErrors mode="RemoteOnly" defaultRedirect="mycustompage.htm"/>
    </system.web>
</configuration&开发者_如何学编程gt;

The problem is that although I change CustomErrors to On I can't see the error, and the xml of the web.config is not malformed since I've tried inducing this error and IIS told me, so it must be something else, but what should I look for?

Edit I Should mention, that I only get this error when I publish my site, web.config doesn't return an error locally, only when I upload to production. I can't even get an html page to display, it still returns the web config error to me

If your using a web.config then I am assuming that you have an ASP.Net application. The web.config stores configurational data for a .NET application. If you don't create an application within your virtual directory then you will see the error you are because there is no application for IIS to serve. This link should help.