Translation:The journalist works at a local channel.
how do you "work at a channel"? That might have made sense before when local stations had assigned channels, but now the local stations are assigned to networks, and the local news and sports can be on all different channels.
I'm not very knowledgeable about how "channels are assigned". this sentence as you can see was created some time ago and we have no way of knowing what the original concept was meant to be. Please give us some idea of how to write a better sentence using this vocabulary so we can avoid errors in the future.
thank you. I wouldn't presume to write a Greek sentence. I assume 'κανάλι" is the proper word in Greek, but I think "station" expresses the work location, if that's what's intended. If it's to express who the employer is, we would say he works "for" or "on" a channel.
I agree - 'on' is better than 'at'. but is marked wrong: https://screenshots.firefox.com/Cv1acT88a5vxQy51/www.duolingo.com