SQL Error

I use the follwing code – it is under developmemt:

	if ($conn->connect_error) {
		die("Verbindungsfehler: " . $conn->connect_error);
	};
    $query = "SELECT post_id FROM spd_postmeta WHERE meta_key='E-Mail' AND meta_value='".$email."'";
	$sql = mysqli_query ($conn, $query);
	if ($sql!= TRUE) {
    	echo "<br>Error: " . $query . "<br>" . $conn->error . '<br>';
	    $post_id = 2393;
	} else {
		$post_id = $conn->post_id;
	    echo $post_id;
	};
    $query = "SELECT meta_value FROM spd_postmeta WHERE meta_key='passwort' AND post_id='".$post_id."'";
    echo $query;
	$sql = mysqli_query ($conn, $query);
    $vpw = $conn->meta-value;
    echo '<br>'.$vpw;

When I use the query in phpMyAdmin it works finde for both queries. In my php code I get no results. I am a novice – what is wrong???