Infintely scrolling texture ends?(only scrolls through once)

Hi, I am currently making a simple 2d game. I wanted to have an endlessly scrolling background(scrolling vertically) so i used a script to make it scroll with the texture offset. Here is my current script:

  #pragma strict
 
 
 private var offsetY : float;
  
 function Update () 
 {
 if (renderer.material.mainTextureOffset.y<0.8){
     renderer.material.mainTextureOffset = Vector2(0,offsetY);
     offsetY += 0.1 * Time.deltaTime;
    
     }
 }

And the plane that it is attached to is a child of the main camera. It scrolls once, but then it ends. Here is a screenshot:

The texture just becomes plain black. Any ideas. (Also my graphics aren't this bad, i'm just starting mechanics).