Agentry - specifying a nested collection for COLLECTION_FIND

I'm having a problem with the rules editor.  I'm trying to create a rule that uses the COLLECTION_FIND function.  The collection property parameter I want to pass to COLLECTION_FIND is a nested collection and will be of type "where rule is true".  In the screen shot below, there should be a child property named "UnitsCollection" that appears under the selected line "First Stations Object Where Rule.....".   Shouldn't all of the properties of the Stations object appear below this line, or am I doing something incorrectly?  Using SMP SDK 3.0.10.3 and Agentry SDK 70.10.0.

Thanks

Tim Sheppard