connect to AD using the System.Web.Security.ActiveDirectoryMembershipProvider provider

I am trying to setup .NET form based authentication with Sharepoint Services 3.0 and Active Directory. I enabled forms and created an appropriate membership provider in the administration page. I followed the instructions on for setting up an  http://technet2.microsoft.com/windowsserver/WSS/en/library/91035419-980e-4230-b3ae-67253b94af4a1033.mspx?mfr=true, and have the following in my web.config file:
 
<connectionStrings>
  <add name="ADConnectionString"
   connectionString=
    "LDAP://ADDRESS/CN=WSIB_Users,DC=WSIB-IIS,DC=wsibdemo,DC=local" />
</connectionStrings>
 
<membership defaultProvider="MembershipADProvider">
    <providers>
        <add name="MembershipADProvider" type="System.Web.Security.ActiveDirectoryMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" connectionStringName="ADConnectionString"
connectionUsername="DOMAIN\Administrator" connectionPassword="PASSWORD" attributeMapUsername="SAMAccountName"/></providers>
        </membership>
 
Restarting IIS and turning on custom error reporting gives me the parser error message:  
 
Parser Error Message: Unable to establish secure connection with the server
 
It also highlights line 84:
Line 82: <membership defaultProvider="MembershipADProvider">
Line 83:     <providers>
Line 84:         <add name="MembershipADProvider" type="System.Web.Security.ActiveDirectoryMembershipProvider, System.Web, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" connectionStringName="ADConnectionString" connectionUsername="wsibdemo\Administrator" connectionPassword="Wsib1234" attributeMapUsername="SAMAccountName"/></providers>
Line 85: </membership>
Line 86:     <httpModules>

Has anybody successfully managed to connect to AD using the System.Web.Security.ActiveDirectoryMembershipProvider provider and what steps did you take?