Grazie ancora per la risposta e la pazienza.

Purtroppo continua a dare errore e nemmeno trovo traccia di microsoft.data.odbc.dll tra i riferimenti di .NET

codice:
Descrizione: Errore durante la compilazione di una risorsa necessaria per soddisfare la richiesta. Rivedere i dettagli relativi all'errore e modificare in modo appropriato il codice sorgente. 

Messaggio di errore del compilatore: CS0117: 'System.Configuration.ConfigurationManager' non contiene una definizione per 'connectionStrings'.

Errore nel codice sorgente:

Riga 10: public void Page_Load (Object sender, EventArgs e)
Riga 11: {
Riga 12:     OdbcConnection myConnectionString = new OdbcConnection(ConfigurationManager.connectionStrings["ConnMySQL"].ConnectionString);
Riga 13:     myConnectionString.Open();
Riga 14: 
 

File di origine: c:\Inetpub\wwwroot\_aspx\Default4.aspx    Riga: 12
web.config
codice:
<?xml version="1.0"?>
<!--
  Per ulteriori informazioni su come configurare l'applicazione ASP.NET, visitare il sito Web all'indirizzo
  http://go.microsoft.com/fwlink/?LinkId=169433
  -->
<configuration>

  <appSettings/>

  <connectionStrings>
    <add name="ConnMySQL" myConnectionString="Driver={MySQL ODBC 5.1 Driver};Server=localhost;Database=com714;uid=root;pwd=XXX;option=3;" providerName="System.Data.Odbc" />;
		<add name="ApplicationServices" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|\aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient"/>
	</connectionStrings>
    
	<system.web>
		<compilation debug="true" targetFramework="4.0">
			<assemblies>
				<add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/></assemblies></compilation>
		<authentication mode="Forms">
			<forms loginUrl="~/Account/Login.aspx" timeout="2880"/>
		</authentication>
		<membership>
			<providers>
				<clear/>
				<add name="AspNetSqlMembershipProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="ApplicationServices" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="false" maxInvalidPasswordAttempts="5" minRequiredPasswordLength="6" minRequiredNonalphanumericCharacters="0" passwordAttemptWindow="10" applicationName="/"/>
			</providers>
		</membership>
		<profile>
			<providers>
				<clear/>
				<add name="AspNetSqlProfileProvider" type="System.Web.Profile.SqlProfileProvider" connectionStringName="ApplicationServices" applicationName="/"/>
			</providers>
		</profile>
		<roleManager enabled="false">
			<providers>
				<clear/>
				<add name="AspNetSqlRoleProvider" type="System.Web.Security.SqlRoleProvider" connectionStringName="ApplicationServices" applicationName="/"/>
				<add name="AspNetWindowsTokenRoleProvider" type="System.Web.Security.WindowsTokenRoleProvider" applicationName="/"/>
			</providers>
		</roleManager>
	</system.web>
	<system.webServer>
		<modules runAllManagedModulesForAllRequests="true"/>
	</system.webServer>
</configuration>
Default4.aspx
codice:
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.Odbc" %>
<%@ Import Namespace="System.Configuration" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

public void Page_Load (Object sender, EventArgs e)
{
    OdbcConnection myConnectionString = new OdbcConnection(ConfigurationManager.connectionStrings["ConnMySQL"].ConnectionString);
    myConnectionString.Open();

    myConnectionString.Close();     
 }  

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title></title>
</head>
<body>
</body>
</html>