vertical aligning LIs within a UL

[DevInCode]

Hi, I have UL that has its height property set around 50px. I want the LIs to be in the middle of it, but I can't seem to get them to co-operate. Am I missing something obvious?

  <style type="text/css">
  ul
  {
     height: 100px;
     background-color: cornsilk;
     vertical-align:  middle;
  }
  ul li
  {
     padding-top: 20px;
     margin:  20px;
     list-style-type: none;
     display: inline;
  }
  </style>
 
 
 
 
     <ul>
          <li>test</li>
          <li>test</li>
          <li>test</li>
          <li>test</li>
          <li>test</li>
          <li>test</li>
 
 
     </ul>