Your Downline is the one from which you earn. So Try to be in touch with your downline and if you have any doubts always be in touch your Upline.
Now coming to your question if you organize a contest for your downline it will create enthusiasm and they will visit and work on and when they work and earn definitely you will earn your commissions.
So try to create an environment where your downline members are comfortable in return you can earn from them.