Vanda propagation- large overgrown plants

[JambaJungle]

I have several old vandas that have grown to over 4'. I have cut the tops off, making sure I included sufficient roots. The bottoms all have large healthy root systems, so I would assume they should sprout a new growth lead. Ten weeks and counting, and no activity. I'm getting continued new root growth, but no new growing leads.
Anyone out there with experience on this? Am I wasting my time? Most of what I have heard says to discard the bottoms, but I have to believe mother nature will kick in and stimulate the plant to survive!