[Zope] Using <dtml-in> to view multiple object types

I am attempting to use the dtml-in tag to view two different types of objects, but am having trouble getting these to display for some reason: This is the code that I am currently using: <dtml-in expr="objectValues('Press_Release') or objectValues('Press_Release_Link')"> </dtml-in> But this is only outputting the Press_Release object and not the Press_Release_Link type. What are the changes that I need to get this to work correctly? - Alex