[Dbix-class] occassional query failure

[Maurice Height]

I am getting an error with code using DBIX::Class which is driving me nuts. 
I have a schema set up as: 

package DB_Schema::History;
use base qw/DBIx::Class/;
__PACKAGE__->load_components(qw/Core/);
__PACKAGE__->table('history');
__PACKAGE__->add_columns(qw/code day open high low close volume/);
__PACKAGE__->set_primary_key(qw/code day/);
1;

In my code I want to get the record with the max value of 'close'
within a period defined by $date to $date2.
Getting the max value of close (ie. $max_close) works fine,
but when I try to retrieve the record that contained the max value
I OCCASSIONALLY get nothing back from the DBIC query which looks
like this:

# Find most recent record that had that max value of 'close'
my $max_close = ...	

my $rs = $schema->resultset('History')->search(
             { code  => $code,
               day   => { '>=', $date1, '<=', $date2  },
               close => $max_close,
             },
             { page     => 1,
               rows     => 1,
               order_by => 'day DESC',
             }
         );
while(my $row = $rs->next) {
    my %record = $row->get_columns;
    print dump(\%record);
}

I have confirmed that the equivalent queries, using the same values
entered into MySQL Query Browser, do work correctly.
For example:

SELECT * FROM history WHERE code = 'TLS' AND close = 3.970
AND day >= '2006-08-16' AND day <= '2006-11-13'; 

I am using DBIx::Class v0.07002 with MySQL v5.0.27-community-nt on 
Windows XP.

Any tips or thoughts would be greatly appreciated.

Thanks
Maurice