UNREAL UE4 - I can´t add Niagara variables to the DataTables, why?

Hi, i cant add Niagara variables (actor, component, etc) to the Structure and make it appear at the Data Tables, i have no problem with the regular particle system, it does appear in the Data Tables, but i cant make my struc´s Niagara variables to appear at the Data Table and all my FX are been made with Niagara, so i need to add them to the Data Tables for all the weapons FX.

If this is a bug, please fix it, if not, please comment on how to make it work, please help!