Dragon stones

I was fighting the 40 stamina kid buu event and I had 6 dragon stones I died two times and used two of my dragon stones but when I died third time and use my third dragon stone it didnt work and when I somehow it took the rest of my dragon stones I was supposed to have 3 left can get the three I lost for no reason.

Cronobrenk about DRAGON BALL Z DOKKAN BATTLE