Animator SetFloat Not Being Recognized

I'm getting this wierd error that says:

Assets/AnimatePlayer.cs(15,34): error CS1061: Type Animator' does not contain a definition for SetFloat' and no extension method SetFloat' of type Animator' could be found (are you missing a using directive or an assembly reference?)

This is my code:

 using UnityEngine;
 using System.Collections;
 
 public class Animate : MonoBehaviour {
     // Use this for initialization
     Animator animator;
     public GameObject player;
     void Start () {
         animator = GetComponent<Animator> ();
     }
     
     // Update is called once per frame
     void Update () {
         if (Input.GetKey(KeyCode.LeftShift)) {
             animator.SetFloat("Speed",1);
         }
     }
 }