How come when I jump my animation stops?

When I hold SHIFT My animation plays smoothly, but when I jump it stops. How do I prevent that?

wait(2)

repeat
    wait()
until game.Players.LocalPlayer

player = game.Players.LocalPlayer
character = player.Character
if not character then
    character = player.CharacterAdded:wait()
end

Mouse = player:GetMouse()
humanoid = character:WaitForChild("Humanoid")
s = humanoid:LoadAnimation(game.StarterPack.WRunAnimScrip.Animation)


Mouse.KeyDown:connect(function(key)
     key = string.lower(key)
   if string.byte(key) == 48 and game.Players.LocalPlayer.TeamColor == BrickColor.new('Bright blue') then
        s:Play()
        humanoid.WalkSpeed = 50
    end
end)


Mouse.KeyUp:connect(function(key)
    key = string.lower(key)
if string.byte(key) == 48 and game.Players.LocalPlayer.TeamColor == BrickColor.new('Bright blue') then
        s:Stop()
        humanoid.WalkSpeed = 16
    end
end)