Select Face operation Null



Hi everyone,
I am trying to select surface and place lighting fixture on it. The surface is the bottom of the railing. Some surfaces can read some of them can’t. You can find my video below. I am getting “Warning: Internal error, please report: Dereferencing a non-pointer.” this type error and can’t find the surface. Why is it happen? Could you help me?

Note: I am using Revit 2015 / Windows 10 / Dynamo 1.2.1
If you need dyn code and file I can share.


Hello @Umit_Balaban1 , pease share the file i will try to figure out