Add Join

if($PostUpVotes = $conn->prepare("SELECT * FROM PostVotes WHERE SubjectName = ? AND VoteType = 'UpVoted'")) {
$PostUpVotes->bind_param('s', $SubjectNamePost);
$PostUpVotes->execute();
$PostUpVotes->store_result();
$postUpVResult = $PostUpVotes->num_rows();

echo "<script>$(\"#UpVoteThis\").html(\"" . "<img src=\\\"UpVoted-Icon.png\\\" width=\\\"30\\\" height=\\\"30\\\"></img> " .  $postUpVResult . "" . "\");</script>";
} else {
	echo "<pre>Error UpVoting, Error: " . $conn->error . "</pre>";
}