Where should ammunition on the GUI be handled?

I have a turret shooting bullets
i have a script called shoottomouse that handles that
i can currently set how many bullets the player has and the gun is clicking when hes out

i want to display the amount of bullets the player has

i created a text box in the unity editor and called it ammoCount

then in my shooting script i did
public Text ammunitionCount;

in my voidUpdate() i did
ammunitionCount.text = ammunition.ToString();

but its not shooting at all now and im getting an error
NullReferenceException: Object reference not set to instance of an object

anyhelp/advice appreciated

 

solved