attempt to index field, a string value?

For some reason in the output it said "Workspace.Map Generator:26: attempt to index field 'Value' (a string value)" for line 26 but when I had the basically the same line of code in other places and it worked fine. Here is the code:

local TopText = script.TopText
while true do
    timer = 60
    repeat
        timer = timer-1
        TopText.Value = "Intermission ("..timer..")"
        wait(1)
    until timer == 0
    TopText.Value = "Picking Random Map..."
    wait()
    m = game.Lighting.Maps:GetChildren()
    r = math.random(1,#m)
    map = m[r]:clone()
    map.Parent = workspace
    TopText.Value = "The Map Chosen Was "..map.Name.."!"
    local Spawn = map.Spawn
    wait(5)
    plrs = game.Players:GetChildren()
    for i = 1, #plrs do
        plrs[i].Character:MoveTo(map.Spawn.Spawn.Position+Vector3.new(math.random(-5,5),0,math.random(-5,5)))
    end
    wait()
    timer = 30
    repeat
        timer = timer-1
        TopText.Value.Text = ""..timer.." Seconds Until The Wall"
        wait(1)
    until timer == 0
    Wall = game.ServerStorage.Wall:Clone()
    Wall.Parent = map
    Wall.Position = Spawn.Position

    map:remove()
end

if you figure out the reason please tell and thank you to in advance if anyone finds the problem.