Why I cannot submit xml?

[admin]

<?php
$xml='
<?xml version="1.0" encoding="iso-8859-1"?>
<Request><Send><Key>123123123</Key><Number>10</Number></Send><BInfo><LName>Pizza</LName><LAddress>somewhere</LAddress><LCity>city</LCity><LState>NY</LState><LZip>112</LZip><LPhone>131313132</LPhone></BInfo></Request>
';

<form method='post' action='script.php'>
<input type='text' name='xml' value='http://www.webdeveloper.com/forum/archive/index.php/<?=$xml?>'>
<input type='submit' name='submit' value='http://www.webdeveloper.com/forum/archive/index.php/submit'>
<form>

What's wrong with this code? Why I cannot submit xml through Post.