Lap Joint Flange offset (AutoCAD P3D 2022)

[sumarni.caga-bulanhagui]

Hi, 

I have created this flange adapter with backing ring, - a lap joint flange set.

When I placed it in between pipe, it works fine but when I change gasket to another, flange offset seem to be zero in value (see attached images).

I am just new to AutoCAD P3D, & as I understand it, flange offset serves as distance for the backing ring from stub end port 1. 

Thanks.

Thanks.