Vertical Box not work with 3D UMG

Im using vertical box to create a dropdown tracklist widget in 3d objects. It was working well when added to viewport but didnt show up in 3d widget. The coordinate space is assigned to world, the UMG was drawn by communicating through BP_Controller and W_Tracklist then casted to BP_Ipod via a widget componet, Im not working with level and game mode yet, all done in actor BP. Does anybody know what I did wrong?