what is rong wth this script? when i press buttons nothing happens



-- ******* Variables ********

green = Color.new(0,255,0)
upPressed = 'You are pressing the "UP" button'
downPressed = 'You are pressing the "DOWN" button'
leftPressed = 'You are pressing the "LEFT" button'
rightPressed = 'You are pressing the "RIGHT" button'
LPressed = 'You are pressing the "L" button'
-- *****Main Loop****** while true do
screen:clear()
pad = Controls.read()
if pad:up() then screen:print(100,100,upPressed,green) end
if pad:down() then
screen:print(100,100,downPressed,green)
end
if pad:left() then
screen:print(100,100,leftPressed,green)
end
if pad:right() then
screen:print(100,100,rightPressed,green)
end
if pad:l() then
screen:print(100,100,LPressed,green)
end
if pad:r() then
screen:print(100,100,'You are pressing the "R" button',green)
end
if pad:triangle() then
screen:print(100,100,'You are pressing the "TRIANGLE" button',green)
end
if pad:circle() then
screen:print(100,100,'You are pressing the "CIRCLE" button',green)
end
if pad:cross() then
screen:print(100,100,'You are pressing the "X" button',green)
end
if pad:square() then
screen:print(100,100,'You are pressing the "SQUARE" button',green)
end
screen.waitVblankStart()
screen.flip()
end