why doesn't this work?

http://pastebin.com/raw.php?i=3RaCFNAZ

im trying to make a gui for my admin, but for some reason, i cant get this part to work!

players = game.Players:GetChildren()
 for i = 1, #players do
local screenGui = Instance.new("ScreenGui", game.Players.players[i].PlayerGui )
local imageLabel = Instance.new("ImageLabel")
imageLabel.Image = "http://www.roblox.com/asset?id=46974682"
imageLabel.Parent = screenGui --up r    l down
imageLabel.Position = UDim2.new(0, 500, 0, 0)
imageLabel.Size = UDim2.new(0, 300, 0, 150)


-- Create TextButton
local textButton = Instance.new("TextButton")
textButton.Parent = screenGui
textButton.Transparency = 1
textButton.Position = UDim2.new(0, 500, 0, 0)
textButton.Size = UDim2.new(0, 300, 0, 150)
textButton.BackgroundColor3 = BrickColor.White().Color
textButton.Text = "Remove RuntoAdmin V.3 GUI"

-- Bind function to button click
textButton.MouseButton1Down:connect(function()
    textButton.Text = "Removing..."

imageLabel.Transparency = 0
t = 1
a = 300
b = 150
while true do


wait(0.05)
a = a-1
b = b-1
imageLabel.Size = UDim2.new(0, a, 0, b)

end
end 
)
end

the error:

attempt to index field "players" (a function value)

please help!