[Zope] Namespace + syntax question

[RC Compaan]

I want to create a list of image thumbnails in a table.  On every tenth item
i want to start a new row.  I thought the "fmod" function is appropriate.  I
get a syntax error however.

My DTML:

<dtml-in "PARENTS[0].objectItems('Image')">
  <dtml-if sequence-start>
     <table><tr>
  </dtml-if>
  <dtml-if "_.fmod(_.['sequence-index'],10)=0">
     </tr>
     <tr><td><dtml-var sequence-item></td>
  <dtml-else>
     <td><dtml-var sequence-item></td>
  </dtml-if>
  <dtml-if sequence-end>
     </tr></table>
  </dtml-if>
</dtml-in>

Any help or other suggestions would be appreciated.

roché