I keep getting errors like "Players is not a member of Root"

[Qwertygiy]

[lua]
while true do
sleep(0.01)
local players = game.Players:getChildren()
[/lua]

Some random point after I start the script:

Error: Players is not a valid member of Root


[lua]
while true do
sleep(0.01)
if game:getService("Players") then
[/lua]

Some random point after I start the script:

Error: getService is not a property of Root