Changing custom animations. Why won't this work?

So I was browsing around and I found a cool script that changes the default roblox animations such as the /e dance emotes, running & more. It works perfectly but I have a sprinting script and when I hold LShift I want it to change my animation. However the walking animation stays the same every time. I Hold shift. Though running still works. Here is my code. Can you tell me why nothing changes?

local mouse = game.Players.LocalPlayer:GetMouse()
local running = false

function getTool()  
    for _, kid in ipairs(script.Parent:GetChildren()) do
        if kid.className == "Tool" then return kid end
    end
    return nil
end


mouse.KeyDown:connect(function (key) -- Run function
    key = string.lower(key)
    if string.byte(key) == 48 then
        running = true
        local keyConnection = mouse.KeyUp:connect(function (key)
            if string.byte(key) == 48 then
                running = false
            end
        end)
        for i = 1,5 do
            game.Workspace.CurrentCamera.FieldOfView = (70+(i*2))
            wait()
        end
        game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 25
        game.StarterPlayer.StarterCharacterScripts.Animate.run.RunAnim.AnimationId = "rbxassetid://1097485671"
        game.StarterPlayer.StarterCharacterScripts.Animate.run.Value = "rbxassetid://1097485671"
        repeat wait () until running == false
        keyConnection:disconnect()
        game.StarterPlayer.StarterCharacterScripts.Animate.run.RunAnim.AnimationId = "rbxassetid://1133938255"
        game.StarterPlayer.StarterCharacterScripts.Animate.run.Value = "rbxassetid://1133938255"
        game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 8
        for i = 1,5 do
            game.Workspace.CurrentCamera.FieldOfView = (80-(i*2))
            wait()
        end
    end
end)