I have TrinityCore x64 (rev 812809a977e2) (3.3.5 branch) up and running on my system, with the latest TDB.
I'm a newbie when it comes to WoW at all, so this might be a dumb question, but I couldn't find any report of this problem anywhere before.
First, the initial skills (Raptor Strike & Auto Shot) won't work with the equipment you have when you first start with your character, not sure if intended.
After I got a new melee weapon Raptor Strike began to work.. The bow is another story though, even though I got a new one, it would say I had no ammo equipped, even though you start with 200 arrows.
I bought another 800 arrows and a new quiver, but it still wouldn't work.. after I removed the arrows from my ammo slot and tried to re-equip it, now it just says that it can't be equipped.
I tried right-clicking from inside the quiver, tried taking the arrows out of the quiver and right-clicking from inside the bag as well, tried manually moving the arrows to the ammo slot from both quiver and bag too. Nothing seems to work.
Strangely enough, as with the starting stuff (weapons and armor alike), the arrows inside the quiver appear with the "?" icon, while inside the shop they show normally (these are Rough Arrows by the way).
This is a Night Elf Hunter, in case the character class/race matters here. I can also see the "Bow" skill in the character's skill list.