Custom Membership Provider not listed in asp.net configuration tool

Question

I have followed the tut here: http://blog.krisvandermast.com/UsingAccessInsteadOfSQLServerForYourASPNETApplicationServices.aspx

I added the dll and the aspnet.mdb files as explained above, my website compiles without error with this web.config

<?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\vx.x\Config 
-->
<configuration>
  <connectionStrings>
    <add name="AccessFileName" connectionString="~/App_Data/ASPNetDB.mdb" providerName="System.Data.OleDb"/>
  </connectionStrings>

    <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.
        -->
        <compilation debug="false">

        </compilation>
        <!--
            The <authentication> section enables configuration 
            of the security authentication mode used by 
            ASP.NET to identify an incoming user. 
        -->
      <authentication mode="Forms">
        <forms loginUrl="mylogin.aspx" defaultUrl="Login.aspx"/>
      </authentication>

      <membership defaultProvider="AccessMembershipProvider">
        <providers>
          <clear/>
          <add name="AccessMembershipProvider"
            type="Samples.AccessProviders.AccessMembershipProvider, SampleAccessProviders"
            connectionStringName="AccessFileName"
            enablePasswordRetrieval="false"
            enablePasswordReset="false"
            requiresUniqueEmail="false"
            requiresQuestionAndAnswer="false"
            minRequiredPasswordLength="1"
            minRequiredNonalphanumericCharacters="0"
            applicationName="SampleSite"
            hashAlgorithmType="SHA1"
            passwordFormat="Hashed"/>
        </providers>
      </membership>      
        <!--
            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="RemoteOnly" defaultRedirect="GenericErrorPage.htm">
            <error statusCode="403" redirect="NoAccess.htm" />
            <error statusCode="404" redirect="FileNotFound.htm" />
        </customErrors>
        -->



    </system.web>

</configuration>

But in asp.net config tool, I can't see listed any provider including mine ? What could be missing then ?