Jquery UI Datepicker doesn't load if input has value

I have the following code

<script type='text/javascript'>

$(function() {

    $( "#datepic开发者_开发技巧ker" ).datepicker({dateFormat:'yy-mm-dd'});

});

</script>

<input type='text' id='datepicker' name='date' value='<?php echo $date_from_mysql_query;?>'>

If the field doesn't have any value, the Datepicker loads, if the field is completed, it doesn't load the Datepicker.

How can I solve this?

Thanks

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my problem actually was to make the datepicker to load on each tagged via id, instead I used the class attribute and it worked marvelous, as I said 6 hrs ago.