datePickers windows ticks returns wrong date.

When using the windows format in the datepicker specified by the dateFormat : '!' the correct date is set upon initialization - but when a user selects e.g the 24 december 2009 the calender returns 633972060000000000 in ticks that translates into 12/23/2009 11:00:00 PM whan using windows (see below)

jquery datepicker initialization:

		    $('#datepicker').datepicker({
		      firstDay: 1, 
		      showOn: 'both',
	  	    selectWeek: true,
	  	    dateFormat: '!',
	  	    defaultDate: '<%=activePeriodStartDate.Ticks%>',
		      onSelect: function(selectedDate) {
		        document.location.href = '_SetActiveDate.aspx?ticks=' + selectedDate;
		      }
		    });

}

ASP.NET C# code:

    string ticks = Request["ticks"];
    long lTicks;
    long.TryParse(ticks,out lTicks);
    DateTime tmpDate = new DateTime(lTicks);