Please double check that you are logged in to your Hue account, going to 'Settings' and check that under 'Hue account' it is written 'Logged in'. If you are not 'logged in', please tap on 'Hue account' > 'Log in' and folow onscreen instructions.
P.s. for out of home control you need to link your Hue bridge to your account. To do this you need to be at home for pressing the puch link button on your Hue bridge.