In earlier versions of the game, beam weapons can't hit ships that are set to shoot asteroids and scoop in the bits (please don't ask me for the flags, I use NovaTools).
Or is it a planet-type weapon? It is possible that the weapon is set to destroy stellar objects. Weapons with this settings can't hit ships.
There is also a flag to prevent it from hitting fast ships and one that prevents it from being fired while the ship is ionized.
Finally there's one that allows you only to fire when you have a key carried aboad.
On the other side, you said it does fire but doesn't hit, right? So the last three ones can be ignored.
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It is interesting that well-protected secrets and complicated puzzles are often solved faster than easy ones. Why? Because the better a secret is protected and the more complicated a puzzle is, the more thinkers it attracts. - me
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