Passing value to reloaded page

Passing value to reloaded page

The code below alerts 28/03/2015 but monitor_reload controller shows only 28.

What am I doing wrong?

Thanks 

<script>
function load_group_stat(item, group_id, start_date, end_date)
  {
    alert(end_date);
    $('#interactions_head').load("<?php echo base_url('monitor_reload/group_stats');?>" + "/" + item + "/" + group_id + "/" + "2015-01-07" + "/" + end_date);
    return false;
  }
</script>