UI Slider not correctly filling

Hello, I was trying to create a health bar but I ran into a problem the slider is not filling even when I have the max value selected can someone help me?

Sorry for bad english

Simply look at the Fill Area gameobject, you will see that there is a right padding in the RectTransform …

I dont think you should be using slider for a health, why not simply change the width of the rect ransform considering the health amount?