Post move called a travel

[TigerBball]

Another basic question from a coach.

This move has generated more traveling calls so I have stopped teaching it, but I think it is legal.

Post player on right block. Player front pivots into lane using right (inside) foot as pivot. Post player pump fakes, defender bites. Post player steps (one step) toward hoop with left foot just to the outside of the defender, lifts pivot foot up going into lay-up motion and lays it in.

When this is called traveling, I try to get a clarification because sometimes my 7th graders let their pivot foot hop backwards when they try to pump fake and make the move to quickly, but that is never the reason given, it is the fact that he lifted his pivot foot when he shot.

I have talked to a ref after the came (calmly) and tried to compare it to picking up the dribble to shoot a lay-up. You get a step and pick up the pivot foot, in this post move, the only difference is he was not dribbling previous to the shoot motion. Is this a correct comparison.