MacBook not going in Sleep mode when lit is closed

Hello guys,

I've tried everything found on the web so far and could not figure this out. Each time I am closing the lid, my MacBook is not going into sleep mode. If I let it like that over the night, the battery will be empty in the morning.

It'a a MacBook Early 2015 1,1 GHz , 8 GB RAM, 256 GB SSD

Any help will be much appreciated!