unABLE TO INSERT FORM DATA INTO DATABASE TABLE

Please i have been trying to insert form data into my database with this code

 $servername = "localhost";
 $user = "Ahmed";
$password = "hammed";
$dbname = "registration"; 
try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $user, $password);
// set the PDO error mode to exception

$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
// check user_error
$checkuserstmt = $conn->prepare("SELECT * FROM user_registration WHERE username= ? && email= ?");
$checkuserstmt->bindParam(1, $username);
$checkuserstmt->bindParam(2, $email);

$checkuserstmt->execute();
if($checkuserstmt->rowcount()==0){

$stmt = $conn->prepare("INSERT INTO user_registration(fname, lname, username, email, pass, gender) 
VALUE (?, ?, ?, ?, ?, ?)");

//bind parameter

$stmt->bindparam(1, $fname);
$stmt->bindparam(2, $lname);
$stmt->bindparam(3, $username);
$stmt->bindparam(4, $email);
$stmt->bindparam(5, $pass);
$stmt->bindparam(6, $gender);

$fname = $_POST['fname'];
    $lname = $_POST['lname'];
    $username = $_POST['username'];
    $email = $_POST['email'];
    $pass = $_POST['pass'];
    $gender =$_POST['gender'];
// use exec() because no results are returned
    $stmt->execute();

if($stmt==false){
        echo "<p>There is already a user with that name: </p>";

}
else{
    echo "New record created successfully. Last inserted ID is: " ;

    $users = $conn->query("SELECT * FROM user_registration");
    $row = $users->fetch();
    echo $row["username"] . " -- " . $row["email"] . "<br />";
}
  }
 }
catch(PDOException $e)
{
echo "Unable to create your account: " . $e->getMessage();
}

$conn = null;

// but instead i get error message first type will be undefined index and the exception error is SQLSTATE[23000]: Integrity constraint violation: 1048 Le champ 'fname' ne peut �tre vide (null)