php - unable to make multiple comments on insert for some reason -

i have made comment section gallery , not sure sure why able 1 comment on wont allow me execute more comment on item

the insert

public function insertcomment() {     if(!get_magic_quotes_gpc()) {         $this -> sanitizeinput();        }             extract($_post);      $name = $_session['username'];     $comment = $_post['comment'];     $productid = $_get['id'];      echo $name;     echo $comment;     echo $productid;       $qry = "insert comments values (null, '$name', '$comment', '$productid' )";      $rs = $this -> db -> query($qry);      if($rs && $this -> db -> affected_rows > 0) {         $msg = 'comment record created. ';         } else {         echo 'error inserting comment';     }     return $msg;       } 

tables

field   type    collation   attributes  null    default   action     id  int(11)         no  none    auto_increment                               name    varchar(150)    latin1_swedish_ci       no  none                                      comment varchar(150)    latin1_swedish_ci       no  none                                      productid   int(11)         no  none 

maybe work

$qry = "insert comments (name, comment, productid) values ('$name', '$comment', '$productid' )"; 

remove null