เปลี่ยนหน้าไม่ได้ค่ะ พอกดไปหน้า 2 มันขึ้น error แต่หน้าแรกก็ขึ้นมาปกติ ไม่ทราบว่าผิดตรงไหน

<? 	
    $id_type = $_REQUEST["id_type"];
	$id_fee = $_REQUEST["id_fee"];
	$id_zone = $_REQUEST["id_zone"];
	include("connectdb.php");
	$sql_count="SELECT COUNT(*) FROM travel WHERE id_type=$id_type AND id_fee=$id_fee AND id_zone=$id_zone ORDER BY id_travel";
	$rs=mysql_query($sql_count) or die(mysql_error());
	$row_data = mysql_fetch_array($rs);
	$num_record = $row_data["COUNT(*)"];
	
	$page_no = $_REQUEST["page_no"];
	$page_size = 4;
	$num_page = ceil($num_record/$page_size);
	$start = $page_size*$page_no;

	$start = $page_size*$page_no;
	$sql="SELECT * FROM travel WHERE id_type=$id_type AND id_fee=$id_fee AND id_zone=$id_zone ORDER BY id_travel 
	      LIMIT $start,$page_size";
	$result=mysql_query($sql) or die(mysql_error());
?>
<fieldset><legend><img src="images/travel2.jpg" width="220" height="60" /></legend>
	<table width="619" height="130" border="0" align="center" cellpadding="9" cellspacing="9">
<?
$count=0;
$colors=array("#FFCCCC","#FFFF99");
while ($row = mysql_fetch_array($result)){
$count++;
?>
<tr>
        <th width="205" height="122" align="center"><img src="<?=$row['pic']?>" width="210" height="126"></th>
        <th width="386" bgcolor="<?=$colors[$count%sizeof($colors)];?>"><div align="left">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
        <a href="read_user.php?id_travel=<?=$row["id_travel"];?>" target="_blank">
          <?=$row["name"];?>
          </a><br>
          </div>
        </div>
          <div align="left"></div>
        <div align="left">
          <p>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
            <?=strip_tags(substr($row["detail"],0,320))."  . . ."?>
          </p>
        </div></th>
  </tr>
<? } 
include("disconnectdb.php");
?>
</table>
<br>
<div align="center">
    <?	
	if($num_record == "0"){
	echo " <strong>ไม่พบข้อมูลที่ท่านค้นหา</strong> ";
	echo "<br>";
	}
	
	if($page_no > 0 ){
	echo " <a href='show.php?page_no=".($page_no-1)."&key=$key'>";
	echo "pre";
	echo "</a>";
	}
	
	for($i=0;$i<$num_page;$i++){
		if($i==$page_no){
			echo "<b>".($i+1)."</b>";
		}else{
		echo " <a href='show.php?page_no=$i&key=$key'>";
		echo $i+1;
		echo "</a> ";
		}
	}
	
	if($num_record != "0" && $page_no < $num_page-1){
	echo " <a href='show.php?page_no=".($page_no+1)."&key=$key'>";
	echo "next";
	echo "</a>";
	}
	
	?>
    </div>
    <br>
    </fieldset>
    <br>