DatePicker start date

Hi all
I'm a new user of jQuery UI and especially DatePicker
But I have some problems with it : I can launch the datepicker from
clicking on a input, but it takes as current date the today date (but
the HTML "value" attribute is not set at this date...).
In fact, DatePicker changes the "apparent" value of my input, not
using the date I implemented in the HTML.
I use the following code on my footer :
<script type="text/javascript">
    $(function() {
        $("#selection_date").datepicker($.datepicker.regional['fr']);
        $('#selection_date').datepicker('option', 'dayNamesMin', ['Di',
'Lu', 'Ma', 'Me', 'Je', 'Ve', 'Sa']);
        $('#selection_date').datepicker('option', 'dayNamesShort', ['Dim',
'Lun', 'Mar', 'Mer', 'Jeu', 'Ven', 'Sam']);
        $('#selection_date').datepicker('option', 'dayNames', ['Dimanche',
'Lundi', 'Mardi', 'Mercredi', 'Jeudi', 'Vendredi', 'Samedi']);
        $('#selection_date').datepicker('option', 'monthNames',
['Janvier','Février','Mars','Avril','Mai','Juin','Juillet','Août','Septembre','Octobre','Novembre','Décembre']);
    });
</script>
Have you any idea ?