ทำระบบตะกร้าสินค้า พอกดสินค้าใส่ตะกร้า แล้ว error อ่ะครับ

[supanat51]

<?
session_start();
$id_prd=$_GET[id_prd];

session_register("sess_id");
session_register("sess_name");
session_register("sess_price");
session_register("sess_num");
if(count($sess_id)=="0") {
$check=1;
} else if (! in_array($id_prd,$sess_id)) {
$check=1;
}
if($check==1) {
include"connecta.php";
$sql="select * from tb_product where id_prd='$id_prd' ";
$result=mysql_db_query($dbname,$sql);
$rs=mysql_fetch_array($result);

$sess_id[]=$rs[id_prd];
$sess_name[]=$rs[name_prd];
$sess_price[]=$rs[price_prd];
$sess_num[]=1;
}
header("LOCATION: basket.php");

[supanat51]

พอกดใส่ตะกร้า


Warning: in_array() [function.in-array]: Wrong datatype for second argument in C:\AppServ\www\basket_add.php on line 11

Fatal error: [] operator not supported for strings in C:\AppServ\www\basket_add.php on line 20