If the animation ID is the problem, how to I get the real one?

local enabled = true
Player = script.Parent.Parent
--Player:WaitForDataReady()
mouse = Player:GetMouse()
run = game:GetService("RunService")
function onKeyDown(key)
if not enabled then return end
enabled = false
	key = key:lower()
	if key == "z" then

local animation = Instance.new("Animation")
		animation.AnimationId = "b126ab943d35e9b7e3bb92379d9504d7"

	local animTrack = humanoid:LoadAnimation(animation)
			animTrack:Play()

	end 	
end

enabled = true


mouse.KeyDown:connect(onKeyDown)

Im not sure if the animation is stopping it from working or if it is the OnKeyDown, please help.

To get your asset Id you need to Export the animation. Do this by going to the animation editor > (Make your animation) Click the + in th upper left hand corner > Click export. When it is finished uploading go to your inventory > Animations > (your animation) Now copy the numbers at the end of the link.

Put the numbers in the script like so:

local enabled = true
Player = script.Parent.Parent
--Player:WaitForDataReady()
mouse = Player:GetMouse()
run = game:GetService("RunService")
function onKeyDown(key)
if not enabled then return end
enabled = false
    key = key:lower()
    if key == "z" then

local animation = Instance.new("Animation")
        animation.AnimationId = "http://www.roblox.com/asset/?id=218192180" --218192180 is an example. Replace it with your ID

    local animTrack = humanoid:LoadAnimation(animation)
            animTrack:Play()

    end     
end

enabled = true


mouse.KeyDown:connect(onKeyDown)