# Why is perlin noise generating flat terrain in Unity?

I am trying to generate terrain using perlin noise however the terrain being generated is a plateau. Here is the code that I'm using:

var xlength = 65.0;
var ylength = 65.0;
var scale = 4.1f;
var heights = new float[xlength, ylength];
function Start () {
for (var i = 0; i < xlength; i++)
for (var j = 0; j < ylength;j++)
heights[i,j] = Mathf.PerlinNoise(Time.time * i / xlength * scale/1000,Time.time * j / ylength * scale/1000)*i*j;
gameObject.GetComponent(Terrain).terrainData.SetHeights(0,0,heights);
}


What am I doing wrong here?

 heights[i,j] = Mathf.PerlinNoise(i / xlength, j / ylength);