title: clang complete doesn't work
body: <p>I installed clang_complete for vim,but it doesn't work. For example: When I typed <code>std::</code> in a c++ file with vim, the bottom of vim's window shows that:</p>
  
  <pre><code>User defined completion (^U^N^P) Pattern not found
  </code></pre>
  
  <p>How can I solve this?</p>