Really rude security staff. On my birthday, a Thursday night, the security guard (North African type, with glasses) wouldn't let us in without any justification even though larger groups of guys came in just before. There was no more reason that we were on a Thursday night, well dressed, and the guard wanted to show himself superior by saying in an arrogant and aggressive tone "It's my call".
If you want to go out in Brussels, I strongly advise against this place, which is small and puts on music that has nothing to do with the Latin atmosphere. I recommend Cartagena, where it's a completely different welcome and a real Latino atmosphere. The boss of the Clave has changed and it is no longer what is explained in the previous comments.