Why does my script think a part doesn't exist?

Hi.

I have a BoolValue that gets set to true when my game starts.

A global script in StarterCharacterScripts (ergo, in all the players) detect when this happens, finds the map that was automatically generated by another script and teleports the player to a part included named PlaceToStart. And before you ask, all of the maps that could be generated contains this part, at least that's what I found, and the part was anchored.

This is the code:

game.Workspace["Special Stuffs"].GameProgress.Changed:Connect(function() -- if the Game Progress has been updated
    if game.Workspace["Special Stuffs"].GameProgress.Value == true then -- if it is updated to say the game has started
        script.Parent.CFrame = game.Workspace.Map:FindFirstChildOfClass("Model").PlaceToStart.CFrame -- teleport to this part
    end
end)

but whenever I run it, I get one of these as an error (never all):

21:37:28.814 - Workspace.KicksForTricks56.GameTeleporter:3: attempt to index a nil value
21:42:38.957 - PlaceToStart is not a valid member of Model
21:45:48.891 - CFrame is not a valid member of Model

I tried using :FindFirstChild() and :WaitForChild(). It didn't give me an Infinite yield warning when I did it so I know it acknowledges that it exists, but it still doesn't think it's a vaild member of the map! I am baffled about why this is happening, especially when I check in Explorer and find it that the part still does exist, both in-game (after I get the error) and in editor mode. Does anybody know what is happening?