This is the code that not getting the result

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" "">
<title>Nice select</title>
<script Language="JavaScript">
function checkData()
    var myTest  = me.D1.value;
	 var req = new Request.JSON({
        url: 'dbselect.php',
        method: 'post',
        data: 'brand=' + encodeURIComponent(myTest)
	 req.addEvent('success', function(response) {
			var ts = new String(response); = ts;



<form method="POST" name="me" id="me">
    <select size="1" name="D1"  onChange="checkData()">
    <option value="99">Default</option>    
    <option value="1">1</option>
    <option value="2">2</option>
    <option value="3">3</option>
    <option value="4">4</option>
    <input name="inter" id="inter"  type="text" >

This is the "dbselect.php" this is working well

$sql="SELECT * FROM tea_type
WHERE id = '$id' ";
$data = mysql_query($sql);
while($info = mysql_fetch_array($data)){
	$model = $info['product'];

echo json_encode($model);

...var req = new Request.JSON where did you define the Request object? It looks like you forgot to "include/import/ling to" a javascript file!