title: mismatch of schema in thinking sphinx
body: <p>I'm working with thinking sphinx</p>
  
  <pre><code>    define_index do
          indexes to
          indexes created_on
          has created_on
      end
  </code></pre>
  
  <p>now while searching on console</p>
  
  <pre><code>    Emaildumps.search 5.day.ago,
      :group_by =&gt; 'created_on',
      :group_function =&gt; :day
  </code></pre>
  
  <p>now the error i get is </p>
  
  <pre><code>     Sphinx Daemon returned error: index emaildumps_core: INTERNAL ERROR: incoming-schema mismatch (in=timestamp created_on:32@160, my=timestamp created_on:32@0)
  </code></pre>
  
  <p>it may be a dumb question but i'm a newbee at sphinx and i can't understand the fundamentals of indexing and searching in it</p>
  
  <p><strong>what am I doing wrong??</strong></p>
  
  <p>so please help me out.</p>