Binding schematic non leaf instance to corresponding layout instance

Hello everyone, 

I'm trying to execute something similar to the binding map reported in this article:

https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1Od0000000nYZuEAM&pageName=ArticleContent

My issue is that I can't figure out a way to overcome this error:

*Error* bndReplaceObjectsBinding: (BND-3026): Cannot add binding to instance ’I0’ because it is not a leaf. Binding can only be set between leaf objects in the schematic and layout objects.

Using the menu Connectivity -> Define Device Correspondence  I have no issue binding the two instances but I can't find a way to execute the same thing trough SKILL codes.

I'm using this code in CIW in order to test it: (Layout is opened in VXL and connectivity reference have been set)

        schematic_obj_id = car(geGetSelSet())    

        ; => db_object

        layout_obj_id = car(geGetSelSet()) 

        ; => db_object   

        cphId=cphGetLayoutXLConfig(layout_id)

        ; =>physical_config_id

        cphSetCellPhysicalBinding(cphId schematic_obj_id~>libName  schematic_obj_id~>cellName layout_obj_id~>libName layout_obj_id~>cellName layout_obj_id~>viewName)

        ; => t

        cphSaveConfig(cphId)

        ; => t

        bndReplaceObjectsBinding(schematic_obj_id layout_object_id)

        ; => *Error* bndReplaceObjectsBinding: (BND-3026): Cannot add binding to instance 'I108' because it is not a leaf. Binding can only be set between leaf objects in the schematic and layout objects.

In the actual SKILL code where I'm processing hundreds of instances I'm using the errset functions to execute this procedure only when required:

errset( bndReplaceObjectsBinding(schematic_obj_id layout_object_id) )

when(errset.errset

          cphSetCellPhysicalBinding(cphId schematic_obj_id~>libName schematic_obj_id~>cellName layout_obj_id~>libName layout_obj_id~>cellName layout_obj_id~>viewName)

          cphSaveConfig(cphId)

          bndReplaceObjectsBinding(schematic_obj_id layout_object_id)

          )

I've tried to apply the solution from the support article but the solution it suggests doesn't seem to work for me or most likely I'm doing something wrong, I'm not really familiar with Physical Configuration and how it affects layouts and schematics.

What I'd like to achieve is a script able to set bindings between non leaf items like Connectivity -> Define Device Correspondence does.

I'm using Virtuoso IC6.1.8-64b.500.26

Does anyone know how to overcome this issue?

Also is there a manual which contains the definition of leaf and non leaf instance?

Thanks in advance,

Dario.