B4W ERROR can't remove object "xx", it must be dynamic and type of MESH or EMPTY.

Hello
I'm trying to delete an object with "m_scs.remove_object (" obj ");" and I don't understand what I'm doing wrong but I have this message: "B4W ERROR can't remove object" xx ", it must be dynamic and type of MESH or EMPTY.

My objects are instances of a MESH made with m_obj.copy ("obj"); They are all dynamic, so I don't understand.

Thanks for help.

Just a mistake I made.

I tested with .is_dynamic and .is_mesh and it wasen't.
I tryed to delete the wrong object.