Unable to insert leads using API

Unable to insert leads using API

Unable to insert leads using API
Code:
<?php

$xml_data ='<Leads>
<row no="1">
<FL val="Lead Source">Web Download</FL>
<FL val="Company">Your Company</FL>
<FL val="First Name">Hannah</FL>
<FL val="Last Name">Smith</FL>
<FL val="Email"> testing@testing.com</FL>
<FL val="Title">Manager</FL>
<FL val="Phone">1234567890</FL>
<FL val="Home Phone">0987654321</FL>
<FL val="Other Phone">1212211212</FL>
<FL val="Fax">02927272626</FL>
<FL val="Mobile">292827622</FL>
</row>
</Leads>';
 
 
$URL = " https://crm.zoho.com/crm/private/xml/Leads/insertRecords?newFormat=1&authtoken=<AUTH_TOKEN>&scope=crmapi&xmlData=";
 
$ch = curl_init($URL);
curl_setopt($ch, CURLOPT_MUTE, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Content-Type: text/xml'));
curl_setopt($ch, CURLOPT_POSTFIELDS, "$xml_data");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$output = curl_exec($ch);
curl_close($ch);

?>

Response:
<response uri="/crm/private/xml/Leads/insertRecords"><error><code>4600</code><message>Unable to process your request. Please verify if the name and value is appropriate for the "xmlData" parameter.</message></error></response>

Please correct me if am doing anything wrong.
Thanks in advance.