What music service do you use? Have you been able to play these stations before?

Not all stations choose to be on TuneIn, there’s many other services that they can be associated with. To name a few, there is myRadio, and iHeart Radio, as well as others available in Sonos. It’s also possible that they have chosen not to associate with any streaming site, and have chosen to stand up their own streaming server, or none at all.  
 

Have you checked with these specific radio stations to see with whom they’ve chosen to be associated with for streaming purposes?

One further suggestion, since you indicate that one plays on the TuneIn website, but not on your Sonos. You may want to ‘reset’ your network connection for the Sonos device. Unplug your Sonos devices from power. While they are unplugged, reboot your router. When the router has come back up, plug back in your Sonos devices. Wait a few minutes, then test again.