Gdzie JEST Błąd

Question

Witam! Czy Ktoś Mógłby mi powiedzieć gdzie jest błąd

<?php
session_start();
$servername = "NAZWASERWERA";
$username = "NAZWAUZYTKOWNIKA";
$password = "HASLO";
$dbname = "NAZWABAZY";

$product = $_POST['parabol'];

$kasa;
$product_id;

$conn = new mysqli($servername, $username, $password, $dbname);

if($product == "ironskyinvasion"){
	$sql = "INSERT INTO user_items (id, ownerId, itemName, imageLink, prize, czyOdebrany) VALUES (NULL, ".$_SESSION['id'].", 'Iron Sky Invasion', 'https://upload.wikimedia.org/wikipedia/en/thumb/4/48/Iron_Sky_Invasion_2012_Title_Image.jpg/250px-Iron_Sky_Invasion_2012_Title_Image.jpg', '71,99', '0')";
	$kasapo = $_SESSION['kasa'] - 71.99;
	$sql2= "UPDATE uzytkownicy SET kasa = '".$kasapo."' WHERE id = '".$_SESSION['id']"' ";
}
elseif($product == "plasmoid"){
	$sql = "INSERT INTO user_items (id, ownerId, itemName, imageLink, prize) VALUES (NULL, ".$_SESSION['id'].", 'Plasmoid', 'https://steamcdn-a.akamaihd.net/steam/apps/1191450/header.jpg?t=1579264700', '71,99' )";
	$kasapo = $_SESSION['kasa'] - 71.99;
	$sql2= "UPDATE uzytkownicy SET kasa = '".$kasapo."' WHERE id = '".$_SESSION['id']"' ";
}
elseif($product == "dinodown"){
	$sql = "INSERT INTO user_items (id, ownerId, itemName, imageLink, prize) VALUES (NULL, ".$_SESSION['id'].", 'Dino Down', 'https://steamcdn-a.akamaihd.net/steam/apps/854160/header.jpg?t=1526022856', '71,99' )";
	$kasapo = $_SESSION['kasa'] - 71.99;
	$sql2= "UPDATE uzytkownicy SET kasa = '".$kasapo."' WHERE id = '".$_SESSION['id']"' ";
}
elseif($product == "theiofthedragon"){
	$sql = "INSERT INTO user_items (id, ownerId, itemName, imageLink, prize) VALUES (NULL, ".$_SESSION['id'].", 'The I Of The Dragon', 'https://steamcdn-a.akamaihd.net/steam/apps/279720/header.jpg?t=1577607281', '25.49' )";
	$kasapo = $_SESSION['kasa'] - 25.49;
	$sql2= "UPDATE uzytkownicy SET kasa = '".$kasapo."' WHERE id = '".$_SESSION['id']"' ";
}
else{
	$sql = "INSERT INTO user_items (id, ownerId, itemName, imageLink, prize) VALUES (NULL, ".$_SESSION['id'].", 'Septerra Core', 'https://static.gry-online.pl/thumbnails/img_241_344/uploads/product-cover/0044/3750/septerra-core-pc-digital.jpg', '17.99' )";
	$kasapo = $_SESSION['kasa'] - 17.99;
	$sql2= "UPDATE uzytkownicy SET kasa = '".$kasapo."' WHERE id = '".$_SESSION['id']"' ";
}


if($conn->query($sql) == true){
	if($conn->query($sql2) == true){
	header('Location: ../Marketplace');
	}
	else{
		echo 'Błąd. Zkontaktuj się z Supportem';
	}
}
else{
	echo 'Wystąpił błąd w zakupieniu Przedmiotu! Zkontaktuj się z Supportem';
}

?>