I'm trying to wire up the members on the site to use .Net Membership from another database.  I've ammended my web.config as follows

<connectionStrings>
    <remove name="umbracoDbDSN" />
    <add name="umbracoDbDSN" connectionString="server=SQLSERVER;database=DATABASE;user id=USER;password=PASSWORD" providerName="System.Data.SqlClient" />
    <!-- Important: If you're upgrading Umbraco, do not clear the connection string / provider name during your web.config merge. -->
    <add name="MYDbDSN" connectionString="server=SQLSERVER;database=MYDATABASE;user id=USER;password=PASSWORD" providerName="System.Data.SqlClient" />
 </connectionStrings>
 <system.web>
    
    ....
    
    <!-- Membership Provider -->
    <membership defaultProvider="MYMembershipProvider" userIsOnlineTimeWindow="15">
      <providers>
        <clear />
        <!--MEMBERS-->
        <add name="UmbracoMembershipProvider" type="umbraco.providers.members.UmbracoMembershipProvider" enablePasswordRetrieval="false" enablePasswordReset="false" requiresQuestionAndAnswer="false" defaultMemberTypeAlias="Another Type" passwordFormat="Hashed" />
        <add name="MYMembershipProvider" 
             type="System.Web.Security.SqlMembershipProvider" 
             connectionStringName="MYDbDSN" applicationName="/"
             enablePasswordRetrieval="false" enablePasswordReset="false" requiresQuestionAndAnswer="false" passwordFormat="Hashed" />
        <!--USERS-->
        <add name="UsersMembershipProvider" type="umbraco.providers.UsersMembershipProvider" enablePasswordRetrieval="false" enablePasswordReset="false" requiresQuestionAndAnswer="false" passwordFormat="Hashed" />
      </providers>
    </membership>
    <!-- added by NH to support membership providers in access layer -->
    <roleManager enabled="true" defaultProvider="MYRoleProvider">
      <providers>
        <clear />
        <add name="UmbracoRoleProvider" type="umbraco.providers.members.UmbracoRoleProvider" />
        <add name="MYRoleProvider" 
             type="System.Web.Security.SqlRoleProvider"
             connectionStringName="MYDbDSN" applicationName="/" />
      </providers>
    </roleManager>
</system.web>

But when I access the members tab in the back office, I'm just getting the spinning disc (in the tree bit).  Any ideas?  Or have I missed something glaringly obvious?