[Zope] Accessing a Subfolder of a Parent Folder

[Asad Habib]

How do I access the subfolder of a parent folder? I am using the following 
but cannot seem to access the folder object:

<dtml-call "REQUEST.set('parentFolder', PARENTS[2].id + 'Test')">
<dtml-call "REQUEST.get('parentFolder').initialize_vars()">

I get the following error:

Error Type: AttributeError
Error Value: 'str' object has no attribute 'initialize_vars'

I understand that a DTML method cannot be called on a string, but how do I 
obtain the object that represents the subfolder 'Test'? Any help would be 
appreciated. Thanks.

- Asad