jquery ui datepicker and mvc view model type datetime

You can look at using the jquery globalize or add the following to your script (assuming of course that the server culture date format is ‘dd/MM/yyy’)

$.validator.addMethod('date', function (value, element) {
  if (this.optional(element)) {
    return true;
  }
  var valid = true;
  try {
    $.datepicker.parseDate('dd/mm/yy', value);
  }
  catch (err) {
    valid = false;
  }
  return valid;
});
$('#dt1').datepicker({ dateFormat: 'dd/mm/yy' });

and please use @Html.ValidationMessageFor(m => m.JobStartDate)