CLOSED: I FORGOT TO CONNECT SOMETHINH THATS WHY IT DIDNT WORK
I have used an damage system before and it worked perfectly fine but now when i tried to use it again the apply damage node not working , i used Print String Node To see where Is the Problem and i found out that the “Apply Damage” Node is called but its not working (BTW I FOUND When i have my mouse on the Damaged actor when the description pop up it say Actor Will be Damaged Currect Value =None )).
Make Sure To Check this Part i think it explain A lot 
Damaged actor is connected to player reffrence that is connected to is valid
Can you send picture of your blueprints where you apply the damage to the actor and the acutal event ? Because it’s not very clear where the issue is.
Thx you helped me a lot I appreciate that , you probably don’t understand how you helped me simply when i was going to take a picture for you i noticed that there is something i forgot to connect and thanks for your help