Mathf.Lerp doesnt work well

Hi, in my game i instantiate various textures onto the scene and animate them along the X-axis with mathf.Lerp.This works fine for the first set that instantiates but the other sets dont animate. Heres my code

//
#pragma strict
    var xStartPosition : float = -1;
    var xEndPosition : float = 0.5;
    var speed : float = 1;
    private var StartTime : float;
    function Start () {
    StartTime = Time.deltaTime;
    }

    
    function Update () {
    transform.position.x =Mathf.Lerp(xStartPosition,xEndPosition,(Time.time-StartTime)*speed);
    }

Any help would be appreciated

Instead of caching Time.deltaTime, cache Time.time instead.