Why is this always returning zero?

I have the following snippet of code:

 using UnityEngine;
 
 public class TestScript : MonoBehaviour 
 {
     public float heightScale;
     public float xScale;
 
     void Start()
     {
         for(int x = 0; x <= 25; ++x)
         {
             float height = heightScale * Mathf.Floor(Mathf.PerlinNoise(xScale * x, 0));
             print(height);
         }
     }
 }

Whenever I input any values for heightScale, and xScale, I always get an output of 0 twenty-five times in the console. Can anyone provide an explanation as to why this is happening?