I could never get the chat to work for me in trade. I finally figured it out in desperation while in Lily's room today. I was using the "Enter" button at the far bottom right of my keyboard. The chat phrases I wrote would just sit there and nothing would happen.
Use the other "Enter" button, near the center of your keyboard. The one with the arrow that points to the left. Everything will work just fine.
Maybe I'm a dope for taking so long to figure this out. But, if someone else is baffled, maybe this will help.