¿Que hago mal?

Hola a todos, estoy trabajando en la oficina y en el servidor declaré en el
IIS un directorio virtual para probar mis códigos, puse el archivo
web.config en el directorio que declaré como raíz en el servidor y le pegué
es siguente código:

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

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

Me sique tirando este error

Server Error in '/emimusic.cl' 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.

Details: To enable the details of this specific error message to be viewable
on remote machines, please create a <customErrors> tag within a "web.config"
configuration file located in the root directory of the current web
application. This <customErrors> tag should then have its "mode" attribute
set to "Off".

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

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

Notes: The current error page you are seeing can be replaced by a custom
error page by modifying the "defaultRedirect" attribute of the application's
<customErrors> configuration tag to point to a custom error page URL.

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

<configuration>
<system.web>
<customErrors mode="RemoteOnly" defaultRedirect="mycustompage.htm"/>
</system.web>
</configuration>



¿Que estoy haciendo mal?


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