textDisplayAddObserver for all player

[AHSS]

i wanna know how to make a text display appears for all players i tried this

textDisplayAddObserver ( textdisplay, getRootElement())

didnt work help plz

[Arran]

for index, player in pairs(getElementsByType("player")) do 
    textDisplayAddObserver(textdisplay, player) 
end 

Just make sure textdisplay is a valid textdisplay.