My BillboardGui won't work?

So I was trying to make this Billboard GUI to work and I want it to spawn on someone's head. And it didn't work, all it said "local character is a 'nil' value" Here ya go.

local player = game.Players.LocalPlayer
local character = player.Character
 
local STATS = Instance.new("BillboardGui")
STATS.Parent = player.PlayerGui
STATS.Adornee = character.Head

STATS.Size = UDim2.new(1, 0, 1, 0)

STATS.StudsOffset = Vector3.new(0, 2, 0)
 
local frame = Instance.new("Frame")
frame.Parent = STATS
frame.Size = UDim2.new(1, 0, 1, 0)
frame.BackgroundTransparency = 0.7
frame.BackgroundColor3 = Color3.new(1, 1, 1)
 
local text = Instance.new("TextLabel")
text.Parent = frame
text.Position = UDim2.new(0.25, 0, 0.25, 0)
text.Size = UDim2.new(0.5, 0, 0.5, 0)
text.Text = "".. game.Players.Data.Beli.Value

I'm familiar with GUI's but not with a Billboard GUI. Please help.