عند إضافة خبر من قبل المشرف تظهر خرابيط

ثانياً تظهر لي هذه الرسالة عند مشاهدة الموضوع من قسم أخبار الأعضاء من هنا :
http://www.XXaaaaaaaXXXX.com/news/pn...ion=open&id=66

وهذه هي الرسالة


Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/XXXXXX/public_html/news/pnews.php on line 102

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/XXXXXX/public_html/news/pnews.php on line 104

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/XXXXXX/public_html/news/pnews.php on line 102

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/XXXXXX/public_html/news/pnews.php on line 104

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/XXXXXX/public_html/news/pnews.php on line 102

Warning: mysql_num_rows(): supplied argument is not a valid MySQL result resource in /home/XXXXXX/public_html/news/pnews.php on line 104

هذه هي السطرين

102
$ar2 = mysql_fetch_array($res2);
104
if(mysql_num_rows($res2) <> 0)

وهذا هو المقطع كاملاً
<?php
$res = mysql_query("SELECT * from $db_pnews order by datum desc");
while ($ar = mysql_fetch_array($res))
{
$res2 = mysql_query("SELECT * FROM $db_topic where topicname='$ar[category]'");
$ar2 = mysql_fetch_array($res2);
$datum = formatTimestamp($ar[datum]);
if(mysql_num_rows($res2) <> 0)
{
echo "
<TR CLASS=MojText>
<TD WIDTH=90><A HREF=?action=open&id=$ar[id]><IMG SRC=gfx/ofolder15.gif BORDER=0></A> <A HREF=?action=edit&id=$ar[id]><IMG SRC=gfx/notes16.gif BORDER=0></A> <A HREF=?action=delete&id=$ar[id]><IMG SRC=gfx/trash.gif BORDER=0></A></TD>
<TD>$ar[headline]</TD>
<TD >$ar[author]</TD>
<TD WIDTH=100>$datum</TD>
<TD><IMG SRC=\"../topic/$ar2[topicimage]\" ALT=\"$ar2[topictext]\" WIDTH=20></TD>
</TR> ";
if ($id == $ar[id]) {echo "<TR><TD></TD><TD COLSPAN=3 Class=MojText BGCOLOR=$color04>$ar[preview]</TD></TR> ";}
}
}