Problem| Health,Damage

the raycast shooting script:

the health script:
the health system attached to the main character.
the raycast system attached to the bullet prefab that instantiated eveytime i shoot.

I have some problems:
1.when i shooting on someone, he got damage, but the current health is not change(updated) on ther health GUI...
**when i shooting on my own collider, the health going down, and the health gui change too**

2.when someone shooting at me, i don't get the hit-i'm no getting damage..