MB pro not going to sleep

Hello all -- I noticed that my MB pro won't go to sleep, either automatically or when I choose it. I can't figure out what's going on, but I think there may be some setting or something going on that I've forgotten about. Can anyone help me out here? El capitan running on the machine.

First thing to try is a SMC reset. If that doesn't work, we can look at something else. Also, we will need more info regarding your MacBook Pro like year and model.