How to get connector's coordinates in a Harness by C# programming?

Hello All:

            I've created a cable harness in Creo/elements/Pro 5.0.  After that I flaten it in to a manufacture asm file. Then I wrote a C# program and try to get every connector's coordinates and other features.  For normal asm file there is no error when I try to get the items in side that assemly , but for the manufacture assmbly , I got below error when I try to get items. Is  CpfcModelItems.ListItems Function can't be used in manufacture asm？How can I deal with this?