Need help with a trick
 

I am trying to learn a maneuver that I am not sure what it is called. I have seen it on the videos and I can do it in G2 and today I did it the first time I tried it but after that I could not repeat it.
It is like a knife edge flip. You fly in a high alfa knife edge and then give full down elevator and the plane flips around the nose back to knife edge. It looks real neat. I tried it later on in the day and it just snapped out into a stall and then into a spin.
What am I doing wrong? It worked perfect the first time but I am not sure what I was doing different.

Thanks
Eldon
Texas