Control Opacity HUD based on health

My problem is really simple but I can’t figure it out :confused:
I’ve a Widget that shows up a blood screen based on my current health.
This is the HUD and you can see that I bind “color and opacity”

In the graph I’ve the same nodes that I use to control the progress bar of the health (it works of course).
So, I divide Health/MaxHealth to obtain a value between 0 and 1. with this value I make a color but I change just the alpha channel.
Why it doesn’t work?

There should be a opacity variable in the material itself. Depending on your health, the opacity is directly proportional to it.

But here is not about Material. it is just an image in a widget and opacity is a value between 0 and 1, so, if I have for example 50/100 health, my result is 0.5 and this value in alpha allows me to see the blood with half opacity. RGB values are set to 1, as default

hp is minus 100 then get absolute value then divide by 100