Im not sure why this sitting animation to a seat wont work?

In Animations theres a thing called priorities. They are used to bypass or not bypass current animations. Use code below, We are going to be using action priority because its the recommended one for animations!

local seat = script.Parent

function SeatIsSatIn(hit)
    if hit.Parent:FindFirstChild("Humanoid") then
        local character = hit.Parent
        local humanoid = character.Humanoid
        wait(0.5) 

        if humanoid:GetState() == Enum.HumanoidStateType.Seated then 

            local animation = Instance.new("Animation")
            animation.AnimationId = "http://www.roblox.com/asset/?id=182435998" 
			animation.Priority = Enum.AnimationPriority.Action

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

            local function StateChanged(oldState, newState)
                if newState ~= Enum.HumanoidStateType.Seated then
                    track:Stop()
                end
            end

            humanoid.StateChanged:connect(StateChanged)
        end
    end
end

seat.Touched:connect(SeatIsSatIn)