[openbox] <application> in rc.xml

[Freddie]

I realise this is a VERY simple question but I'm looking for help in getting an 
<application> tag working. I've a number of these that are working fine but I 
have one with which I'm having issues.

     <application class="Iceweasel">
       <desktop>3</desktop>
       <maximized>yes</maximized>
       <focus>no</focus>
     </application>

$ xprop WM_CLASS
WM_CLASS(STRING) = "Navigator", "Iceweasel"

I've tried it with name="Navigator" and with both name and class specified with 
no luck. What is it that I've stuffed up?

Cheers,
Freddie