i want create multiple search where statement $where_search is a multiple condition from post form. but stil error when iam using this code ".where_search." in where condition with mysql_num_rows for paging

 $tampil2 = mysql_query("SELECT * FROM bb where ".$where_search."  and kd_kelompok='2' and kd_komoditi='11' and nm_sebutan IS NOT NULL " );

this is the complete code.

$where_search = "kd_pok='2' and kd_komoditi='11' ";
    if (isset($_POST['lakpus']))
    {


        if (empty($_POST['lakpus']))
        {

        }
        else
        {

        if (empty($where_search))
        {
            $where_search .= "lakpus = '$lakpus' ";

        } 
        else
        {

            $where_search .= "AND lakpus = '$lakpus' ";

        }
        }
    } 

    if (isset($_POST['kd_por']))
    {
        $kd_por = $_POST['kd_por'] ;

        if (empty($_POST['kd_por']))
        {

        }
        else
        {

        if (empty($where_search))
        {
            $where_search .= "kd_por = '$kd_por' ";

        } 
        else
        {

            $where_search .= "AND tab1.kd_por = '$kd_por' ";

        }
        }
    } 
        $max=15;
        $tampil2 = mysql_query("SELECT * FROM bb where ".$where_search."  and kd_kelompok='2' and kd_komoditi='11' and nm_sebutan IS NOT NULL " );
        $jml = mysql_num_rows($tampil2);
        $jmlhal  = ceil($jml/$max);