[Zope] Trouble Creating Instance of Custom Product Programmatically

[Dan Shafer]

I thought I had understood the instructions at Zope.org but I'm doing 
something wrong.

I have a custom Zope Product called PI_Clearing. It has several ZClasses in 
it, including one called Clearing. I want to set up a Web fom with which 
the user creates a new instance of a Clearing object. Following what I 
understand of the directions, I have this DTML method called startClearing:

dtml-call "REQUEST.set('id', 'New Clearing')
dtml-with "manage_addProduct['Clearing']"
  dtml-call "Clearing_add"
/dtml-with

(Angle brackets removed.)

But nothing ever gets created. Clearing_add is the default add method 
created when I defined the Product and the Class. I've tried adding a 
dtml-call to set the ID of the object before calling the Clearing_add 
process. No luck.

I get no error messages or anything, just no results.

What am I not understanding?