Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in C:\AppServ\www\orange\inventory.php on line 54

<?PHP
$strSQL = "SELECT * FROM inventory ORDER BY inven_id";
$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");
$Num_Rows = mysql_num_rows($objQuery);

$Per_Page = 1;   // Per Page

$Page = $_GET["Page"];
if(!$_GET["Page"])
{
	$Page=1;
}

$Prev_Page = $Page-1;
$Next_Page = $Page+1;

$Page_Start = (($Per_Page*$Page)-$Per_Page);
if($Num_Rows<=$Per_Page)
{
	$Num_Pages =1;
}
else if(($Num_Rows % $Per_Page)==0)
{
	$Num_Pages =($Num_Rows/$Per_Page) ;
}
else
{
	$Num_Pages =($Num_Rows/$Per_Page)+1;
	$Num_Pages = (int)$Num_Pages;
}

$strSQL .=" order  by inven_id ASC LIMIT $Page_Start , $Per_Page";
$objQuery  = mysql_query($strSQL);
?>
<table border="1" cellspacing="0" bordercolordark="#CCFF00" width="100%">
	<tr>
    	<th>ลบ</th>
    	<th>ลำดับ</th>
        <th>S/N</th>
        <th>ประเภท</th>
        <th>รุ่น</th>
        <th>ประกัน / ปี</th>
        <th>จำนวน</th>
        <th>แก้ไข</th>
    </tr>
    <?PHP
	while($objResult = mysql_fetch_array($objQuery)) // error บรรทัดนี้
	{
		if($bg == "white")
		{
			$bg = "#CCCCCC";
		} 
	else
		{
				$bg = "white";
		}
	?>
    <tr bgcolor="<?=$bg;?>">
    	<td align="center"></td>
    	<td align="center"><?=$i;?></td>
        <td align="center"><?=$objResult['inven_id'];?></td>
        <td align="center"><?=$objResult['inven_type'];?></td>
        <td><?=$objResult['inven_model'];?></td>
        <td align="center"><?=$objResult['inven_contract'];?></td>
        <td align="center"><?=$objResult['inven_quantity'];?></td>
        <td align="center">แก้ไข</td>
    </tr>
    <?
	}
	?>
</table>

<br>
Total <?= $Num_Rows;?> Record : <?=$Num_Pages;?> Page :
<?
if($Prev_Page)
{
	echo " <a href='$_SERVER[SCRIPT_NAME]?Page=$Prev_Page'><< Back</a> ";
}

for($i=1; $i<=$Num_Pages; $i++){
	if($i != $Page)
	{
		echo "[ <a href='$_SERVER[SCRIPT_NAME]?Page=$i'>$i</a> ]";
	}
	else
	{
		echo "<b> $i </b>";
	}
}
if($Page!=$Num_Pages)
{
	echo " <a href ='$_SERVER[SCRIPT_NAME]?Page=$Next_Page'>Next>></a> ";
}
mysql_close($objConnect);
?>