Poisoned Weapons=Poisoned missiles?

So last week my Master of Poisons Dark Elf Pirate was busily coating his crossbow bolts with Dark Venom and I overhear from the next table. "The crossbow is St 4, St 5 with Dark Venom". And our new player replies, "you can't do that! Dark Venom can only be used on melee weapons." Hmmm. We've used it on missile weapons for years, but we've played rules wrong for years before. The rulebook gives the example of a poisoned sword but I didn't read anything prohibiting poisoning an arrow or bolt.

Am I missing something?

Why shouldn't it be allowed to use it on missile weapons? I mean, really, why?

Only things I can't see it being used on are blackpowder weapons. Poisoned throwing knives, crossbows, javelins, bows are all fine. They have enough surface to coat in whatever poison while still holding the item, small lead balls don't.

not only do they not have enough surface, the explosive fire is likely to burn the poison off when fired at the enemy...

After some quick research you should be able to poison most weapons except for black powder.

Thanks everyone for the replies. Thought you could...