why do I keep getting No method name passed in __namecall for Object?

local x = 81.6
local y = -10.1
local z = -52
local Map = game.ServerStorage.Maps
local Maps = game.ServerStorage.Maps:GetChildren()

    -- Map selection
local function mapchoice()

    local Choose = Maps[math.random(1,#Maps)]
    Choose.Name = "ChosenMap"
    local placemap = Choose:Clone() 
    placemap:SetPrimaryPartCFrame(CFrame.new (x, y, z))
    placemap.Parent = game.Workspace()

end 

    wait (Resttime)
    mapchoice()

I've been stuck on these lines of code for months.