Getting php error on production but not development

[eluser]Cgull[/eluser]
Sorry, another thing, this function is being called in a view with an ajax call:

Code:

$(document).ready(function()
{
var delivery = $('#delivery').val();
var weight = $('#sendform').serialize();

$.ajax({
    type: "POST",
    url: "<?php echo base_url(); ?>order/checkout/calcDelivery",
    data: {delivery: delivery, weight: weight},
    success: function(data){
    $('#deliveryCalc').html(data);
    $('#deliveryVal').val(data);
    var total = 'R ' + (parseFloat($('#totalval').val())).toFixed(2);
    $('#total').html(total);
   }
  });

And there is no redirect in the checkout controller file at all.