[Zope] URL param string problem

Hi All, I have a DTML method which needs to concat a URL. We have: <dtml-with expr="web_client('http://192.168.1.1/tinorb/pieex2.php?imageName=CA')"> <dtml-var body> </dtml-with> There is a variable &dtml-theImageName; which needs to replace the CA in the above code with the value of &dtml-theImageName; (which is equal to OH). I tried doing something like <dtml-let theURL="_['http://192.168.1.1/tinorb/pieex2.php?imageName='+theImageName]"> But i get the following key error, which has the exact URL i want to pass to web_client (see above) but it's not working. Any thoughts?? Error Type: KeyError Error Value: http://192.168.1.1/tinorb/pieex2.php?imageName=OH Thanks, m