Flashing material as a HUD Image?

I’m trying to add to my HUD an image of an arrow that flashes at variable frequency. I created a texture of an arrow from a png file and made it into a material, then I varied the colour by a square wave. The blueprint of the resulting material is shown here:

My issue is that, when I try to add this to the HUD Widget, it comes up with a black background. On the other hand, the texture from which it came has no black background. This difference is shown here:

I’m wondering, is there any way to remove the black background? I want my material to be dynamic, but it seems that I can’t get just a plain arrow. Any help would be really appreciated thanks!

Activate the opacity in the material properties material. And connect the alpha.