Why won't this left arm movement work properly? (CFrame)

[AVCOIL3D (AVCOIL)]

Recently I have been working on a Zombie Tower game, but I have had a problem with the gun. In the script, it makes first person arms follow the camera, but only the right arm works. Here is the script.

local player = game.Players.LocalPlayer
local mouse = player:GetMouse()

game["Run Service"].RenderStepped:Connect(function()
	local rightX, rightY, rightZ = player.Character.Torso["Right Shoulder"].C0:ToEulerAnglesYXZ()
	player.Character.Torso["Right Shoulder"].C0 = (player.Character.Torso["Right Shoulder"].C0 * CFrame.Angles(0, 0, -rightZ)) * CFrame.Angles(0, 0, math.asin((mouse.Hit.p - mouse.Origin.p).unit.y))

	local leftX, leftY, leftZ = player.Character.Torso["Left Shoulder"].C0:ToEulerAnglesYXZ()
	player.Character.Torso["Left Shoulder"].C0 = (player.Character.Torso["Left Shoulder"].C0 * CFrame.Angles(0, 0, -leftZ)) * CFrame.Angles(0, 0, math.asin((mouse.Hit.p - mouse.Origin.p).unit.y))
end)

Here is what happens:

Any help is appreciated.

[Geolio9 (Tomate)]

On the last line, put a negative before math.asin()
I would imagine this is necessary because the axes are inverted.

[AVCOIL3D (AVCOIL)]

Yes, this works. Thank you so much!