Why doesnt it pick random?

I'm trying to make a randomize cube picker and it spawns randomly were the CubePlaces CFrame are, But it didnt work.

The output said something about an nil value.

local CubeDisplays = game.ReplicatedStorage.CubeDisplay:GetChildren()
local CubePlaces = game.Workspace.CubePlaces:GetChildren()
local CubePlacesPart = game.Workspace.CubePlaces
CubeDisplay = math.random(1, #CubeDisplay)
CubeChosen = CubeDisplay[CubeDisplay]
CubeChosen:Clone().Parent = game.Workspace
CubeChosenClone = CubeChosen:Clone()
CubeChosenClone.Parent = game.Workspace
CubePlace = math.random(1, #CubePlaces)
CubeChosenClone.CFrame = CubePlace.CFrame

Here's a fix, it should work :

local CubeDisplays = game.ReplicatedStorage.CubeDisplays:GetChildren()
local CubePlaces = game.Workspace.CubePlaces:GetChildren()
local CubePlacesPart = game.Workspace.CubePlaces

CubeDisplays = math.random(1, #CubeDisplays)
CubeChosen = CubeDisplays[CubeDisplays]
CubeChosen:Clone().Parent = game.Workspace
CubeChosenClone = CubeChosen:Clone()
CubeChosenClone.Parent = game.Workspace
CubePlace = math.random(1, #CubePlaces)
CubeChosenClone.CFrame = CubePlace.CFrame

You forgot the "s" after "CubeDisplay".

I'm not sure why, but to fix it just put math.randomseed(tick()) before you use math.random