Engineer loadout - Turret / Ammo pack

[satori]

It looks like both the turret and the ammo pack should fall into the ability slot. I never actually unlocked the turret (but I somehow have it) and I do have the first (free i think) level for the ammo pack, however, in the loadout screen I only have the turret as an option in the ability slot. Strangely, in the loadout screen, I have the ammo pack option in the utility slot which won't allow me to equip both the ammo pack and mines. Is this a glitch? Or (more likely) am I doing it wrong? Thanks