搜索分页不起作用

Question

I am facing problem of pagination with searching not working.I am trying to paginate data with searching but there are no data paginate on second and third page.please help me.here is my code.

function paginationData($str,$num,$start,$sql,$perpage){
  $pagination = new Pagination; 
  $config['base_url'] = $str;
  $config['total_rows'] = $num;
  $config['per_page'] = $perpage;
  $config['cur_page'] = $start;
  $config['prefix'] = '&p=';
  $config['next_link'] = 'Next';
  $config['prev_link'] = 'Previous';
  $pagination->initialize($config); 
  $sql .= " LIMIT ".$start." , ".$config['per_page'];
  $res = qry($sql,2);   
  $data['listArr'] = $res;  
  $data['Total'] = $num;    
  $data['links'] =  $pagination->create_links();
  $data['per_page'] = $config['per_page']; 
  return $data;
}

$where = '';
$order_by = " ORDER BY parent_id,id_category ASC";  
$search = '';
$search = $_REQUEST['search'];
$search_term = $_REQUEST['word_search'];
if(@$search_term)
    $where = " where name like '%".$search_term."%'";
$sql = "select id_category,name,parent_id from category".$where.$order_by;      
$total_rec = qry($sql,3);
$page = $base_url.'categories.php?word_search='.$search_term;
$start = $_GET['p']?$_GET['p']:0;
//echo "<pre>";
//print_r ($total_rec);
//die();
$perpage=10;
$data = paginationData($page,$total_rec,$start,$sql,$perpage);