Error while create integrated 3d objects in AR i.e. Object reference not set to an instance

I am creating a project for interior using AR foundation and arcore for android by following along this video tutorial on youtube but as I click on box open it is showing me this error…Any help will be appreciated. (I am totally new to coding and unity. just following along the tut)

i get the answer,so the problem was that the position of my raw image and text was different in hierarchy…after assigning to it properly it slve