I'm a TA for a class on graduate-level Digital Signal Processing, and one of my responsibilities is to lead a discussion session. It's a 50-minute session that happens once a week, and the professor teaches the class for 3 hours in the week. 

The professor had suggested that I discuss the solutions to the homework problems in this session, so today for my first session, that's what I did. 

However, I felt this was quite a waste of time, since everyone who had had problems in the homework had come to my office hours and got them cleared, and everyone else in class had managed to do the problems. While I went through solving the problems on the board, I wanted to actively engage the students by throwing in questions about details, what-ifs, some important tricks to remember, etc. But it was a mostly unresponsive, bored-looking class with frown faces.

Should I not go through the homework solutions, and instead focus on important topics covered in lectures? 

Also any ideas on how to lead a discussion session in a way that the students who actually managed to do the homework (which is the vast majority of the class) don't get bored?