Mysql insert query isn't working in php file?

<?php
error_reporting(0);
    $firstName = $_POST['firstName'];
    $lastName = $_POST['lastName'];
    $gender = $_POST['gender'];
    $email = $_POST['email'];
    $password = $_POST['password'];

    // Database connection
    $conn = new mysqli('localhost','root','','farming');
    if($conn->connect_error){
        echo "$conn->connect_error";
        die("Connection Failed : ". $conn->connect_error);
    } else {
        echo "connection ok"; 
        $stmt = $conn->prepare("insert into registration(firstName, lastName, gender, email, password, phone) values( ?, ?, ?, ?, ?)");
        $stmt->bind_param("sssss", $firstName, $lastName, $gender, $email, $password);
        $stmt= $stmt->execute();
        echo "Registration successfully...";
        $stmt->close();
        $conn->close();
    }
?>

I am new to php and trying to insert some values to my database table but query isn't working when I am passing values by php variables. This query was working properly manually but not in php form