Player Health

I'm currently working on the UI programming for the game. Right now, I'm creating a canvas and writing the script for the health bar. Displaying the bar itself was no problem at all, however writing a script for the health bar is another issue. So far, I didn't encounter any errors but the character's health isn't decreasing for every damage that is taken. I will make adjustments to the health bar as soon as I fix the script. The health bar is located at the bottom left of the image below.