php提交表单不能得到值

reg.php
-------------------------------------------------------------
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gbk2312" />
<title>php</title>
</head><body>
<center>User Register</center>
<fieldset>
<form method="post" action="post.php" name="f1">
 <table border="0" cellspacing="4" cellpadding="0" align="center" width="200">
  <tr>
   <td align="right">user:</td>
   <td><input type="text" name="user" id="user" size="12" /></td>
  </tr>
  <tr>
   <td>password:</td>
   <td><input type="password" name="psw" id="psw" size="12" /></td>
  </tr>
  <tr>
   <td align="right">sex:</td>
   <td><input type="radio" name="rdo" id="rdo" checked="checked" value="male" />male
       <input type="radio" name="rdo" id="rdo" value="woman" />woman</td>
  </tr>
  <tr>
   <td align="right">age:</td>
   <td><input type="text" name="age" id="age" size="1" /></td>
  </tr>
  <tr>
   <td valign="top" align="right">person:</td>
   <td><textarea name="meum" id="meum" rows="15" cols="30"></textarea></td>
  </tr>
  <table align="center" width="200">
  <tr>
   <td><input type="submit" name="sub" id="sub" value="submit" /></td>
   <td width="100"><input type="reset" id="rst" name="rst" value="reset" /></td>
  </tr>
  </table>
 </table>
 </form>
</fieldset>
</body>
</html>post.php
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<?php include "conn.php" ?>
<?php 
   echo "print: ".$_request['user']."<br>";
echo "print: ".$_request['psw']."<br>";
echo "print: ".$_request['age'];
?>提不到值，怎么回事哦？