Can't reference to any volume in level blueprints

So,after I split my main level into multiple levels,I want to add a trigger volume to my main level and use it in blueprints.But,I can’t find a reference to it.This is happening with any volume,but it works with static meshes or characters.

As seen,the volume is selected,but…

no reference to it.
I really need some help.
Thank you!

are you using any kind of level streaming?

Did you try right clicking on trigger box, and right in the bottom clicking add-event