The following code throws a TransactionAbortedException with message "The transaction has aborted" and an inner TransactionPromotionException with message "Failure while attempting to promote transaction":

    using ( TransactionScope transactionScope = new TransactionScope() )
    {
        try
        {
            using ( MyDataContext context = new MyDataContext() )
            {
                Guid accountID = new Guid( Request.QueryString[ "aid" ] );
                Account account = ( from a in context.Accounts where a.UniqueID.Equals( accountID ) select a ).SingleOrDefault();
                IQueryable < My_Data_Access_Layer.Login > loginList = from l in context.Logins where l.AccountID == account.AccountID select l;

                foreach ( My_Data_Access_Layer.Login login in loginList )
                {
                    MembershipUser membershipUser = Membership.GetUser( login.UniqueID );
                }

                [... lots of DeleteAllOnSubmit() calls]

                context.SubmitChanges();
                transactionScope.Complete();
            }   
        }

        catch ( Exception E )
        {
        [... reports the exception ...]
        }
    }

The error occurs at the call to Membership.GetUser().

My Connection String is:

      <add name="MyConnectionString" connectionString="Data Source=localhost\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=True"
   providerName="System.Data.SqlClient" />

Everything I've read tells me that TransactionScope should just get magically applied to the Membership calls. The user exists (I'd expect a null return otherwise.)