无法从我的PHP脚本循环发送推送通知

Question

I need to send push notification to many users. I have saved their push notification key in my database. I am trying to send it in a loop but it only sends first push notification and after that it gives following error:

Fatal error: Call to a member function fetch_assoc() on a non-object in /home/theacademicpoint/public_html/tapadmin/webservices/sendPostNotification.php on line 39

Following is my code for calling the push notification script:

$sql = "SELECT distinct users.userid, firstname, lastname, userType, title, device, pushkey FROM student_course, users where users.userid!=".$userid." and users.userid= student_course.userid and ucid in (".implode(',',$arrUserCourse).") ORDER BY firstname";
                    $result = mysqli_query($con,$sql);
                    while($row = $result->fetch_assoc())
                    {
                        $device = $row["device"];
                        echo $row["firstname"];
                        if($device=="ios"){
                                $deviceToken = $row["pushkey"];
                                $message = "New Post added from ".$user;
                                include('push.php');
                            }
                    }
                }

If I comment out call to php script(push.php) the loop runs completely without any error. But if I uncomment it like above, it gives error as mentioned above. Though the loop still executes completely.

Regards
Pankaj