Datatable requested unknown parameter '2' from data source row 0

yocsan

Hello I'm having issues trying to show data from my DB, I can show each data from the table in my DB but when I try to show all in a table it gives the error in the title, I don't know why. I'm using codeigniter.

This is the controller function

public function datatable()
{

$this->datatables->select('name', 'user_id', 'last_name','identify','contact','rol_type')       
    ->unset_column('user_id')
    ->add_column('actions', get_buttons('$1','users'),'user_id')
    ->from('users')
    ->where(array('user_status'=>'1'));

echo $this->datatables->generate();

}
User_id is an autoincrement variable.

This is the view page.

<?php
//set table id in table open tag
$tmpl = array ( 'table_open' => '

<

table id="big_table" border="1" cellpadding="2" cellspacing="1" class="mytable">' );
$this->table->set_template($tmpl);

$this->table->set_heading('Name','Last Name','Identify Card','Contact Number','Rol assign,'Actions');
echo $this->table->generate();

<?php > ?>

$(document).ready(function() {

var oTable = $('#big_table').dataTable( {
    "bProcessing": true,
    "bServerSide": true,
    "sAjaxSource": '<?php echo base_url(); ?>users/datatable',
            "bJQueryUI": true,
            "sPaginationType": "full_numbers",
            "iDisplayStart ":20,
            "oLanguage": {
                "sUrl":'<?php echo base_url(); ?>users/translate'
    },
            "fnInitComplete": function() {
            //oTable.fnAdjustColumnSizing();
                },
            'fnServerData': function(sSource, aoData, fnCallback)
                {
                    $.ajax
                    ({
                      'dataType': 'json',
                      'type'    : 'POST',
                      'url'     : sSource,
                      'data'    : aoData,
                      'success' : fnCallback
                    });
                }
} );

} );

</script>
I use the datatable code for other functions on my program and it works, and even showing more than 4 data selected.

The data I'm showing it has integer, and strings.