My iMac won't streaming live radio

Make sure you are signed into iTunes if you already are sign out and back in.

This forum covers pre-2006 iMacs and there are a lot of things they cannot do. Can you give us more info on your computer so we can tell which of the hundreds of iMac variants you have. Also please tell us your Mac OSX version. "iOS" as currently shown in your profile cannot run on computers, only Apple's mobile devices.