defaultDate problem

defaultDate problem


I don't know if i'm missing something, but i can't seem to set a
default date on my datepicker.
$("#begindate,#enddate").datepicker({
    beforeShow: customRange,
    defaultDate: new Date("<?php echo date('Y-m-d 00:00:00', $_GET
['begindate']); ?>"),
    dateFormat: $.datepicker.ATOM
});
And the output ends up like this:
$("#begindate,#enddate").datepicker({
    beforeShow: customRange,
    defaultDate: new Date("2008-12-01 00:00:00"),
    dateFormat: $.datepicker.ATOM
});
if i put a alter for that value it gets out ok, so i'm really
stumped...
Test page: http://www.palliscience.com/analysis/