The explosions don't work

I’m experimenting more with the body programming blocks (I forgot what they were called), and I decided to make a project where if you open your hand, an explosion appears. The problem is that… there are no explosions. It’ll show you an error alert when you press the flag. I know why it doesn’t work, but I don’t know how else to code it. (the code being the sprite following your hand.)

The explosion really work but after the body gestures system sets up, in reality,
it does not work in the first instance but it occurs after, like the big integers library.