php添加文章部分代码求解

1，addarticle.php
<html>
<head>
<meta http-equiv="content-type" content="text/html;charset=utf-8"></head>  <form action="addarticleProcess.php" method="post">
<input type="submit" value="发布话题"   "> 
<textarea  name="B1" rows="50" cols="152" style="width: 500px; height: 295px"> 
</textarea>
</form></html>
2,addarticleProcess.php<?phpecho $_POST['B1'];?>点击提交后，显示 
 Notice: Undefined index: B1 in D:\wamp1\www\blog\addarticleProcess.php on line 3这和添加文章代码不行啊，求解决方案