To validate the photo, it has to contain all the two subjects:

1. Fire extinguisher
2. Child

Your one contains the second, but there isn't a fire extinguisher, so it isn't a valid entry.

Then, if you'll find a photo containing them, you'll have to indicate also a third key-subject that your photo contains: it is mandatory.

I hope you can find a valid photo to join. In the meantime, have a nice day :)