datepicker value

datepicker value

Hi, I try to set up datepicker input field value, but it is always set to today, the code as following:
<input type="text" id="datepicker" name="report_date" value="<?php echo $report_date; ?>" onChange="ChangeDueDate(this.value)">

$report day is not today, but the datepicker always display today.

Could anyone help?

Thanks

henry