Erro Mysql

if(!isset($_COOKIE["cbanner"])) {

 $stmt1 = $mysqli->prepare("SELECT * FROM wp_posts ORDER by RAND()");

 $stmt1->execute();

 if($res1 ->get_result($stmt1)){;

 $rows1 = $res1->num_rows;

 if($rows1) {

 $row = $res1->fetch_assoc();

 $id_link = $row["ID"];

 $link_url = $row["guid"];

 $ad_click = $row["adclick"];

 if($ad_click == 1) {

 $stmt2 = $mysqli->prepare("UPDATE wp_posts SET adclick=adclick+1 WHERE id=?");

 $stmt2->bind_param("i", $id_link);

 $stmt2->execute();

 

E aí pessoal,BLZ? estou com o seguinte erro: Fatal error: Call to a member function get_result() on a non-object in

 Alguém poderia me auxiliar para O problema?