a dire la verità funziona adesso.
ho ridotto però così il mio file web.config

va bene ugualmente ?
cosa rappresenta di preciso questo web.config ? ci sono documentazioni in merito ? (in italiano pls)

ecco il file

codice:
<?xml version="1.0"?>
<!-- 
    Note: As an alternative to hand editing this file you can use the 
    web admin tool to configure settings for your application. Use
    the Website->Asp.Net Configuration option in Visual Studio.
    A full list of settings and comments can be found in 
    machine.config.comments usually located in 
    \Windows\Microsoft.Net\Framework\v2.x\Config 
-->
<configuration>
	<appSettings/>
	<system.web>
		<!-- 
            Set compilation debug="true" to insert debugging 
            symbols into the compiled page. Because this 
            affects performance, set this value to true only 
            during development.
        -->

		<!--
            The <authentication> section enables configuration 
            of the security authentication mode used by 
            ASP.NET to identify an incoming user. 
        -->
		<authentication mode="Windows"/>
		<!--
            The <customErrors> section enables configuration 
            of what to do if/when an unhandled error occurs 
            during the execution of a request. Specifically, 
            it enables developers to configure html error pages 
            to be displayed in place of a error stack trace.

        <customErrors mode="Off" defaultRedirect="GenericErrorPage.htm">
            <error statusCode="403" redirect="NoAccess.htm"/>
            <error statusCode="404" redirect="FileNotFound.htm"/>
        </customErrors>
        -->
    <customErrors mode="Off"/>
	</system.web>
</configuration>
grazie daniele80

a presto