Cookie is not getting set in PHP

I am building a minor website and for that I am saving a cookie to further continue my code properly but cookie is not getting set then I have copy and paste same cookie setting code on another test page and on that page cookie is getting set properly but same code is not setting cookie here I don't know why please assist me although my code is pretty big so I am uploading below the only cookie setting part: `

    <?php
    if($val == 1){
      if(!isset($_COOKIE['id_cookie'])){
    //Fetching id
          $sql = "SELECT id from user ORDER BY id DESC LIMIT 1";
          $result = mysqli_query($con,$sql);
          $id = mysqli_fetch_assoc($result);
          $id = implode($id);
    
      //Creating cookie
        setcookie('id_cookie', $id, time()+( 365 * 24 * 60 * 60), "/");
    
      if(isset($_COOKIE['id_cookie'])){
          echo "Cookie values is set: ".$_COOKIE['id_cookie'];
      }else{
        echo "Failed!";
      }
`

Here each time I am getting failed message of else means cookie is not getting set