The reception on them isn't the greatest so try to make sure you route the speaker cables over the top of the head within the helmet. The speaker cables are actually the aerial.
It also helps to download the update software from the Cardo website and use it to preset some known strong stations in your area.
The radio in my Schuberth SRC didn't work at all until I did the latest software upgrade and even now the reception isn't great but sometimes can work brilliantly.