Issue in updating records

I am trying this code to update the record in leads.
Using the ZSC key in authtoken. But I get this error "HTTP Response status code: 200
>> Time taken 5121
15-Feb-2013 16:37:58 org.apache.commons.httpclient.HttpMethodBase getResponseBody
WARNING: Going to buffer response body of large or unknown size. Using getResponseBodyAsStream instead is recommended.
postResp=======><response><error><code>4600</code><message>Unable to process your request. Please verify whether you have entered proper method name,parameter and parameter values.</message></error></response>

"

Code:

import java.io.*;
import java.util.*;
import java.net.*;
import org.apache.commons.httpclient.*;
import org.apache.commons.httpclient.methods.*;
import org.apache.commons.httpclient.methods.multipart.Part;
import org.apache.commons.httpclient.methods.multipart.FilePart;
import org.apache.commons.httpclient.methods.multipart.StringPart;
import org.apache.commons.httpclient.methods.multipart.MultipartRequestEntity;
import org.apache.commons.httpclient.methods.multipart.PartSource;
import org.apache.commons.httpclient.methods.multipart.ByteArrayPartSource;

public class updateRecords
{
    public static void main(String a[])
    {
       try
       {
           //----------------------------Fetch Auth Token ----------------------
           String authtoken = "6bb297a5cf5bc298eec9de2bf9f7690d";//If you don't have a authtoken please refer this wiki https://zohocrmapi.wiki.zoho.com/using-authtoken.html
           String scope = "crmapi";
           String recordId = "754788000000142035";
           String newFormat = "1";

           String targetURL = "https://crm.zoho.com/crm/private/xml/Leads/updateRecords";
           String paramname = "content";
           String xmlDataString = "<Leads><row no=\"1\"><FL val=\"Company\">Zoho</FL><FL val=\"First Name\">Scott</FL><FL val=\"Last Name\">James</FL><FL val=\"Annual Revenue\">11111.0</FL><FL val=\"Mobile\">999999999999</FL></row></Leads>";

           PostMethod post = new PostMethod(targetURL);
           post.setParameter("authtoken",authtoken);
           post.setParameter("scope",scope);
           post.setParameter("newFormat",newFormat);
           post.setParameter("id",recordId);
           post.setParameter("xmlData",xmlDataString);

           HttpClient httpclient = new HttpClient();
           PrintWriter myout = null;

           // Execute http request
           try
           {
               long t1 = System.currentTimeMillis();
               int result = httpclient.executeMethod(post);
               System.out.println("HTTP Response status code: " + result);
               System.out.println(">> Time taken " + (System.currentTimeMillis() - t1));

               // writing the response to a file
               myout = new PrintWriter(new File("response.xml"));
               myout.print(post.getResponseBodyAsString());

               //------------Get response as a string ----------
               String postResp = post.getResponseBodyAsString();
               System.out.println("postResp=======>"+postResp);
           }
           catch(Exception e)
           {
               e.printStackTrace();
           }
           finally
           {
               myout.close();
               post.releaseConnection();
           }
       }
       catch(Exception e)
       {
           e.printStackTrace();
       }
    }
}