I just tested it and it works fine.
But I found something. If you click on "Gun 1" and Press "Cancel" instead of "Ok", it still shows you a message "Invalid Weapon ID". It's just a little something, but still kinda annoying though. And if possible, you should add a Weaponlist, so you can simply choose the weapon you want and don't have search the number of the weapon you want. Just a thought.
Edit: I just bought a Perk with Rapid Fire on and my Weapons/Knife disappeared and it seems like the game "freezes". The Zombies move and attack but you can't do anything. You can't open doors or buy new weapons.