ติดปัญหาเกี่ยวกับการค้นหาแบบมีเงื่อนไขครับ เวลาค้นหาแล้วค่า id ที่ผม where มามันไม่ส่งเวลาผมค้นหาอะครับ

<?PHP
	REQUIRE ("connectdb.php");
		$id = $_REQUEST['zone_id'];
		$sqlZone = "select * from psm_tbzone where zone_id = '$id'";
		$resultZone = mysql_query($sqlZone) or die(mysql_error());
		$rowZone = mysql_fetch_array($resultZone);
PHP?>
<table width="900" class="table_H" cellpadding="0" cellspacing="0"  bgcolor="#0066FF" >
	<tr bordercolor="#FFFFFF" height="30">
		<td>
			<center><font color="#FFFFFF">รายงานอายุงานพนักงาน เขต&nbsp;<?=$rowZone['zone_name']?></font></center>
		</td>
	</tr>
</table>
	<form name="frmSearch" method="get"  action="<? echo $_SERVER['SCRIPT_NAME'];?>">
		<? include "template/function_date.php";?>
						<table class="table_S" align="center" cellpadding="0" cellspacing="0">
							<tr>
								<td colspan="7" align="right" bgcolor="">
									<table width="300" border="0" align="left">
											<tr align="right" valign="bottom">
												<td width="100" align="right"><FONT SIZE="2" COLOR="#330000">ค้นหาข้อมูล ::&nbsp;</FONT></td>
												<td width="120" align="left">
													<input name="txtKeyword" type="text" id="txtKeyword" value="<?php $_GET["txtKeyword"];?>">
												</td>		
												<td width="10" align="left"><input type="image" src="images/images-icon/001_37.png" width="20" height="20" alt="ค้นหา" /></td>
												<td width="30" align="left"><input type="button" onclick="history.back();" value="ยกเลิก" class="button0"></td>
											</tr>
										</table>
								</form>
							 </tr>
<? 
$txtKeyword = $_GET["txtKeyword"]; 
?>
<table width="900" class="table_B" cellpadding="0" cellspacing="0">
	<tr align="center" bgcolor="#044064" height="30">
		<TD width="30"><span class="style-column">ลำดับ</span></TD>
		<TD width="150"><span class="style-column">ชื่อ - นามสกุล</span></TD>
		<TD width="150"><span class="style-column">ตำแหน่ง</span></TD>
		<TD width="100"><span class="style-column">พื้นที่ปฏิบัติงาน</span></TD>
		<TD width="50"><span class="style-column">สังกัด</span></TD>
		<TD width="50"><span class="style-column">วันที่เริ่มงาน</span></TD>
		<TD width="50"><span class="style-column">อายุงาน</span></TD>	
	</tr>
<? 		

$id = $_REQUEST['zone_id'];

 $sql_total="SELECT
psm_tbzone.zone_code,
psm_tbzone.zone_name,
psm_tbzone.zone_id,
ps_tblocation.location_name,
psm_tbtitle.title_name,
ps_tbperson.ps_name,
ps_tbperson.ps_surname,
psm_tbposition.position_name,
ps_tbworking.wk_datestar,
psm_tbbelong.belong_name
FROM
psm_tbzone
Inner Join psm_tbbelong ON psm_tbzone.zone_code = psm_tbbelong.zone_code
Inner Join ps_tblocation ON psm_tbbelong.belong_id = ps_tblocation.belong_id
Inner Join ps_tbperson ON ps_tbperson.location_id = ps_tblocation.location_id
Inner Join psm_tbtitle ON psm_tbtitle.title_id = ps_tbperson.title_id
Inner Join psm_tbposition ON psm_tbposition.position_id = ps_tbperson.position_id
Inner Join ps_tbworking ON ps_tbworking.working_code = ps_tbperson.working_code

where psm_tbzone.zone_id='$id' ";

if($txtKeyword){


$sql_total .=" AND belong_name like '%$txtKeyword%'"; }  

	$result_total=mysql_query($sql_total)or die("Error Query[".$sql_total."]");
	$total = mysql_num_rows($result_total);
	$sql_show=$sql_total;
	$result_show=mysql_query($sql_show)or die(mysql_error());
	$totalp = mysql_num_rows($result_show);

	if($totalp<=0)
		{
			echo  "<script language='javascript'>alert(' ไม่พบข้อมูล ! ');history.back();</script> ";
		}
	
			while($row_show=mysql_fetch_array($result_show))
		{
		$a++; 
			if($bg == "#f7f7f7") { //ส่วนของการ สลับสี 
			$bg = "#f7f7f7";
			$bd="#f7f7f7";
			} else {
			$bg = "#f7f7f7";
			$bd = "#f7f7f7";
			}

			$today = date("Y-m-d");	
			$datestar = $row_show['wk_datestar'];
			
			list($byear, $bmonth, $bday)= explode("-",$datestar);
			list($tyear, $tmonth, $tday)= explode("-",$today); 
			
			$mdatestar = mktime(0, 0, 0, $bmonth, $bday, $byear);
			$mnow = mktime(0, 0, 0, $tmonth, $tday, $tyear );
			$mage = ($mnow - $mdatestar);
			
			 "วันที่เริ่มงาน $datestar"."<br>\n"; 
			 "วันที่ปัจจุบัน $today"."<br>\n";
			 "รับค่า $mage"."<br>\n";
			
			$u_y=date("Y", $mage)-1970;
			$u_m=date("m",$mage)-1;
			$u_d=date("d",$mage)-1;

		 "$u_y <b>ปี</b> $u_m <b>เดือน</b>";


			$YearAge = $u_y;
			$monthAge = $u_m;
	?>


							<TR bgcolor="<? echo $bg?>" onMouseOver="this.style.backgroundColor ='#77BBFF'" onMouseOut="this.style.backgroundColor='<?=$bg?>'">
								<TD align="center" width="35" height="17"><span class="style-text"><?=$a?></span></TD>
								<TD align="left" width="150" height="17"><span class="style-text">&nbsp;<?=$row_show['title_name']?><?=$row_show['ps_name'];?>&nbsp;&nbsp;<?=$row_show['ps_surname']?></span></TD>
								<TD align="left" width="150" height="17"><span class="style-text"><?=$row_show['position_name']?></span></TD>
								<TD align="left"  width="100" height="17"><span class="style-text"><?=$row_show['location_name']?></span></TD>
								<TD align="left" width="50" height="17"><span class="style-text"><?=$row_show['belong_name']?></span></TD>
								<TD align="left"  width="60" height="17"><span class="style-text">&nbsp;<?=Datethai2($row_show['wk_datestar'])?></span></TD>
								<TD align="left"  width="60" height="17"><span class="style-text">&nbsp;<? echo "$YearAge <b>ปี</b> $monthAge <b>เดือน</b>"; ?></span></TD>
								</TD>
							<?}?>
							</TR>
						</table>
						<table  width="900" class="table_H" cellpadding="0" cellspacing="0" >
							<tr >
   								 <td align="right">
									<font color="#000000" size="2">
										<? printf("มีพนักงานทั้งหมด <strong>%d</strong> คน ",$total);?>
									</font>
								 </td>
  							</tr>
						</table>