Try this :
function shout(player, cmd, msg)
local accountname = getAccountName(getPlayerAccount(player))
if isObjectInACLGroup ( "user." .. accountname, aclGetGroup ( "Admin" )) then
for id, players in ipairs(getElementsByType("player")) do
local message = tostring(msg)
local textDisplay = textCreateDisplay ()
local nombre = getPlayerName(player)
textItem = textCreateTextItem ( message, 0.5, 0.5 )
textDisplayAddText ( textDisplay, textItem )
textDisplayAddObserver ( textDisplay, players )
setTimer ( textDestroyTextItem, 2500, 1, textItem )
setTimer ( textDestroyDisplay, 2500, 1, textDisplay )
end
else
outputChatBox("",player,255,255,255)
end
end
addCommandHandler("teles", shout)