HudBlueprint to Levelblueprint

Im new to unreal I have a problem with the communication from Hud_Blueprint to Level_Blueprint

I want to have a slider in the Hud which controls the rotation of a cube in the level

In the Hud_Blueprint i have the slider i made in a Widget_Blueprint. Works perfect, printline values from 0 to 1 I tried to use a Interface_Blueprint, like in the following link without success. Pass Variable from HUD Blueprint to Level Blueprint - UI - Unreal Engine Forums

my Blueprints: Dropbox - Error

Seems like i have no connection between the Blueprints.

The function works just in the Hud_Blueprint.