Simulating Simple HTML form Post using HttpWebRequest..

Hi guys...
I have a problem posting xml Data using HttpWebRequest..
The server returns Internal error..

I want to simulate a simple Form with Method=Post. The form have three fields. Two for credentials and the third one for Posting XML. Here is the sample HTML which i want to simulate using HttpWebRequest..
<form action="https://myurl.com/samplepage.cfm" method="post" >
integration_id<input type="text" name="integration_id" value="id" /><br />
integration_pwd<input type="text" name="integration_pwd" value="pwd"  /><br />
<textarea name="hrxml" style="height: 404px; width: 593px">
<?xml version="1.0" encoding="UTF-8"?>
<BackgroundCheck account="test" userId="test" password="test">
  <BackgroundSearchPackage>
...