[Scripting Question] Attacking move that set Weather fails by some reason

[ExplosiveLogin]

The move in question is supposed to deal damage then set up a Hail. In the first attempt, I tried to set the moves function code in the PBS to be the same as Hail, and while the move works fine in the first use, it completely fails the second time. Then I tried to add a pbAdditionalEffect to set Hail if Hail is not already up, like this:

class PokeBattle_Move_300 < PokeBattle_WeatherMove
  def pbAdditionalEffect(user,target)
    @weatherType = :Hail if ![:Hail].include?(@battle.pbWeather)
  end
end

And now the move just fails regardless. I assume is something in the PokeBattle_WeatherMove that's forcing the move to fail, but if I try to set it as a regular damaging move (as in, use PokeBattle_Move_300 < PokeBattle_Move), the move deals damage but the Weather doesn't start. I'm just really confused, and help would be much appreciated.