How do I find channel of audio and pass it to chopto SOP

Hi, I passed in chan1 from null but my chopto SOP could not find the channel. Where am I suppose to look at which channel is the audio in?

here’s the screenshot :

are you sure it’s called chan1? you can middle click the chop to see the channel name (can’t see it in the pic ) or choose the channel on the
choptosop with the triangle at the right of the Channel name field.