Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource

<?php
	include('db.php');
						
	$abfrage = mysql_query("SELECT * FROM DB126517.sofahocker_news ORDER BY DESC");
	$anzahl = mysql_num_rows($abfrage);
						                				
	for ($i=0; $i<$anzahl; $i++)
	{
		$thema = mysql_result($abfrage, $i, "thema");
		$beschreibung = mysql_result($abfrage, $i, "beschreibung");
							

		echo"<font face='Courier New, Courier, mono'>";
		echo"$thema";
		echo"</FONT>";
		echo"
";
		echo"<FONT FACE='Arial,Helvetica' size='-3'>";
		echo"$beschreibung";
		echo"</FONT><HR noshade>";
	}
?>

".....  ORDER BY DESC"