Prepared statements in mysqli not working - mysql

Question

Can someone explain to me why this isn't working. Trying to convert to prepared statements as per the advice of everybody but get stuck right at the beginning...the connection is fine and it returns no message, but there is no entry into my table (called nametable)
<?php
$dbhost = "localhost";
$dbuser = "root";
$dbpass = "fidelio";
$dbname = "test";
$con = mysqli_connect($dbhost, $dbuser, $dbpass, $dbname);
if(mysqli_connect_errno()) {
die("Database connection failed: " .
mysqli_connect_error() .
" (" . mysqli_connect_errno() . ")");
}
$query = "INSERT INTO nametable (fname, lname) values (?,?)";
$stmt = mysqli_prepare($con, $query);
$firstName = "simon";
$lastName = "morris";
mysqli_stmt_bind_param($stmt,"ss",$firstname, $lastname);
mysqli_stmt_execute($stmt);
printf("Error: %s.\n", $stmt->error);
$stmt->close();
?>
I added the last 2 lines and the error that comes back is
Error: .
This works just fine but the prepared statements do not....anyone know why?
$sql="INSERT INTO nametable (fname, lname)
VALUES ('$firstName', '$lastName')";
if (!mysqli_query($con,$sql))
{
die('Error: ' . mysqli_error($con));
}

Answer 1

try this
$dbhost = "localhost";
$dbuser = "root";
$dbpass = "fidelio";
$dbname = "test";
$mysqli = new mysqli($dbhost, $dbuser, $dbpass, $dbname);
$firstName = "simon";
$lastName = "morris";
if ($stmtb = $mysqli->prepare("INSERT INTO nametable (fname, lname) values (?,?)")) {
$stmtb->bind_param('ss',$firstName, $lastName);
$stmtb->execute();
}else {printf("Prepared Statement Error: %s\n", $mysqli->error);}