Mysql_fetch_row() expects parameter 1 to be resource, null given in

<?php

	include 'header.php';
	include 'db/db_connect.php';

// time interval (86400 seconds = 1 day)
//$interval = 86400;
// time interval (3600 seconds = 1 hour)
$interval = 3600;
$timeframe = $_POST['timeframe'];
if (!$timeframe) 
	$timeframe=2;
$timeframeInMs = date("YmdHis", time() - $timeframe*$interval);

// Query

$query = "(SELECT id,

                 date_format(changed, '%Y-%m-%d %H:%i:%s') as changed

          FROM   dog

          WHERE  changed > $timeframeInMs)

					UNION 

					(SELECT dog_id, date_format(changed, '%Y-%m-%d %H:%i:%s') as changed

					 FROM photos_dog

					 WHERE changed > $timeframeInMs)

					UNION 

					(SELECT dog_id, date_format(changed, '%Y-%m-%d %H:%i:%s') as changed

					 FROM breeders_dogs

					 WHERE changed > $timeframeInMs)

					UNION 

					(SELECT dog_id, date_format(changed, '%Y-%m-%d %H:%i:%s') as changed

					 FROM owners_dogs

					 WHERE changed > $timeframeInMs)					 					 

					ORDER BY changed DESC";

$result = mysql_query($query) or die('Query failed: ' . mysql_error());

?>


<div class="main">
	<div class="content" >
		<div style="float:left">
			<h3>Newest Dog Updates </h3>
		</div>
		<div style="float:left;padding-left:30px;padding-top:18px">
			<form action="newest.php" method="post">
			<label>Current timeframe: </label> 
			<select name="timeframe" onChange="javascript:submit();">
				
				<option value="24" <?php if($timeframe == "24") echo "selected='selected'"; ?>>the last 24 hours</option>			
				<option value="72" <?php if($timeframe == "72") echo "selected='selected'"; ?>>the last 3 days</option>
				<option value="168" <?php if($timeframe == "168") echo "selected='selected'"; ?>>the last week</option>
				<option value="336" <?php if($timeframe == "336") echo "selected='selected'"; ?>>the last 2 week</option>
			</select>
			</form>
		</div>
		<div style="text-align:right;float:right">				
			<img src="images/TWA_logo_square_colored_18px_green.gif"> <label>Most important data available</label><br>
			<img src="images/TWA_logo_square_colored_18px.gif"> <label>Important data is missing </label>

	  	</div>

		<div style="clear:both">
		<table width="95%"><tr><td valign="top">
		<?php 

			echo "<table id='newest'>\n";

			$dogs = array();

			while ($line = mysql_fetch_row($result)) {

				$dogid = $line[0];

				$timestamp = $line[1];

				if ($dogs[$dogid]<$timestamp)

					$dogs[$dogid]=$timestamp;

			}

			foreach ($dogs as $key => $value) {

				$dquery = "SELECT name,creator,last_modifier,sire_id,dam_id,sex,yearofbirth,yearofdeath,color

						FROM dog

						WHERE id = $key";

				$dresult = mysql_query($dquery) or die('Query failed: ' . mysql_error());

				$dline = mysql_fetch_array($dresult);
				
				//
				if (($dline['yearofdeath'] == null)) {
				if (($dline['sire_id'] == null) || ($dline['dam_id'] == null) || ($dline['sex'] == null) || ($dline['yearofbirth'] == null) || ($dline['color'] == null)) {
					$imgIcon = 'images/TWA_logo_square_colored_21px.gif';
					$tooltipText = 'Important info missing';
				} else {
					$imgIcon = 'images/TWA_logo_square_colored_21px_green.gif'; 
					$tooltipText = 'Most important info available';
				} 
				} else {
						$imgIcon = 'images/TWA_logo_square_noir_21px.gif';
						$tooltipText = 'This dog is dead';
				}
				?>			
				<tr><td><img src='<? echo $imgIcon ?>' onmouseover="Tip('<? echo $tooltipText ?>', WIDTH, 170, BGCOLOR, '#CADCEB', BORDERCOLOR, '#115098',
							FONTCOLOR,'#354A6A',FONTFACE,'verdana,geneva,sans-serif',FONTSIZE,'10px', SHADOW, true, 
							SHADOWCOLOR,'#115098', SHADOWWIDTH,3,PADDING,2)"/>				
				<?
				echo "<a href='details.php?id=$key'>$dline[name]</a></td>\n";
				echo "\t\t<td><label>($value)</label></td>\n";
				
				if ($_CURRENT_USER->can_see_user_actions()) {
					$creatorQuery = "SELECT username,userid FROM users WHERE userId = '$dline[creator]'";
					$creatorResult = mysql_query($creatorQuery) or die('Query failed: ' . mysql_error());
					$creatorLine = mysql_fetch_row($creatorResult);
					$modifierQuery = "SELECT username,userid FROM users WHERE userId = '$dline[last_modifier]'";
					$modifierResult = mysql_query($modifierQuery) or die('Query failed: ' . mysql_error());
					$modifierLine = mysql_fetch_row($modifierResult);	
					//echo "\t\t<td><label> created by: <a href='php_users/htdocs/profile.php?id=".$creatorLine[1]."'><b>$creatorLine[0]</b></a>, last modified by: <a href='php_users/htdocs/profile.php?id=".$modifierLine[1]."'><b>$modifierLine[0]</b></a></label></td>\n";
				}
				
				$q="SELECT photo_id FROM photos_dog WHERE dog_id=$key";
				$r = mysql_query($q) or die('Query failed: ' . mysql_error());
				if ($l = mysql_fetch_object($r)) {		
					if ($l != null)
						?>
						<td><img src='images/camera.png' style="opacity: .8;filter: alpha(opacity=80);" 
						onmouseover="this.T_WIDTH=95;this.T_BGCOLOR='#e7e7e7';
						this.T_BORDERCOLOR='#cc9966';this.T_FONTCOLOR='#333333';
						this.T_FONTFACE='verdana,geneva,sans-serif';this.T_FONTSIZE='10px';
						this.T_SHADOWCOLOR='#cc9966';this.T_SHADOWWIDTH=3;this.T_PADDING=2;
						return escape('photo available')"/></td>
						<?php
				}
   			echo "\t</tr>\n";

			}

			echo "</table>\n";			

		?>
		<p> </p>
		
		<div style="clear:both">
		<?php 

			echo "<table>\n";

			while ($pline = mysql_fetch_row($presult)) {

				echo "\t<tr><td style='padding-left:40px'><a href='managePerson.php?personId=$pline[0]'>$pline[1] $pline[2]</a></td>\n";

				echo "\t\t<td><label>($pline[3])</label></td>\n";					

	   			echo "\t</tr>\n";

			}

			echo "</table>\n";			

		?>
		</div>

		</td>
		<td valign="top" align="right" style="width:130px;padding-left:30px;padding-top:20px; padding-bottom:200px">
			<?php /*
			<script type="text/javascript"><!--
				google_ad_client = "pub-1096996726337786";
				google_ad_width = 120;
				google_ad_height = 600;
				google_ad_format = "120x600_as";
				google_ad_type = "text_image";
				google_ad_channel = "";
				google_color_border = "FFFFFF";
				google_color_bg = "eeeeee";
				google_color_link = "CC9966";
				google_color_text = "333333";
				google_color_url = "CC9966";
			//--></script>
			<script type="text/javascript"
		  		src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
			</script> */ ?>		
		</td>
		</tr></table>
		</div>

	</div>
</div>

<?php 
	include 'footer.php';
?>

peut être faut-il que je trouve d'où provient la variable $presult?