<colgroup> validerer ikke med w3c

Hi,

Jeg kan ikke få min tabel igenne w3c's HTML validering - det er elementer colgroup der giver mig problemer.

Tag nu fx denne tabel:

<table border="1" width="100%" cellspacing="1" ID="Table1" summary="Table 1. Correlations between sedentary and physically active behaviours for weekdays and weekends (bold)">
  <caption>
    Table 1. Correlations between sedentary and physically active behaviours for
    weekdays and weekends (bold)</caption>
  <col span="1" width="20%" id="text">
  <colgroup span="4" width="20%" id="value">
    <thead>
      <tr>
        <th id="th1">&nbsp;</th>
        <th id="th2" axis="behaviour category">TV viewing</th>
        <th id="th3" axis="behaviour category">Computer games</th>
        <th id="th4" axis="behaviour category">Computer and internet</th>
        <th id="th5" axis="behaviour category">Sum of 9 sedentary behaviors</th>
      </tr>
    </thead>
    <tbody>
      <tr>
        <td headers="th1" scope="row" axis="activity category">Sport & exercise</td>
        <td headers="th2">-.07 / <strong>-.01</strong></td>
        <td headers="th3">.11 / <strong>.04</strong></td>
        <td headers="th4">-.04 / <strong>.05</strong></td>
        <td headers="th5">-.15 / <strong>-.11</strong></td>
      </tr>
      <tr>
        <td headers="th1" scope="row" axis="activity category">Active travel</td>
        <td headers="th2">-.15 / <strong>-.07</strong></td>
        <td headers="th3">-.08 / <strong>-.04</strong></td>
        <td headers="th4">.03 / <strong>-.03</strong></td>
        <td headers="th5">-.21 / <strong>-.01</strong></td>
      </tr>
    </tbody>
</table>