I'm trying to use the tablesorter plugin (http://tablesorter.com/docs/) to sort a table and having issues with it sorting the correct column of data.  The table that I'm sorting has a colspan on the header rows and this seems to be causing the plugin to sort the table by a different column then desired.

<table class="tablesorter">

<thead>

<tr>

<th>Stuff</th>

<th colspan="2">Value 1</th>

<th colspan="2">Value 2</th>

<th colspan="2">Value 3</th>

</tr>

</thead>

<tbody>

<% @things.each do |thing|%>

<tr>

<td><%=link_to thing.name, thing%></td>

<td class="num"><%=thing.value_1%></td>

<td class="meta sml"><%=thing.value_1_change%></td>

<td class="num"><%=thing.value_2%></td>

<td class="meta sml"><%=thing_value_2_change%></td>

<td class="num"><%=thing.value_3%></td>

<td class="meta sml"><%=thing.value_3_change%></td>

</tr>

<% end %>

</tbody>

</table>

 When clicking the Value 1, Value 2, and Value 3 headers I want the columns that are holding those values to be used for the sort.

Any advice or recommendations on how to achieve that with the tablesorter plugin?  Or perhaps there is a better plugin to use?

Thanks, Steve