getConstraintId returns zero with soft bodies I want to create some constraints in BGE with phyton (between a soft body and a dynamic object) and then remove them after a while. I tried this code to save constraint's id:

import bge

p = bge.logic.getCurrentScene().objects["Plane"].getPhysicsId()

o = bge.logic.getCurrentController().owner

o["c"] = bge.constraints.createConstraint(o.getPhysicsId(), p, 1, 0.0, 0.0, 0.0).getConstraintId()


the constraint created and all of parameters seems to be correct but getConstraintId always returns zero and I can't understand why?
As an experience I understand that Blender's Game Engine can't create constraints on Soft Bodies dynamically by bge codes. Actually it creates the constraints but you don't have any access to them.