Can't Identify Culprit for Error

I'm getting an error message that the "type or namespace 'rockStates' can't be found' and that I might be missing a "using directive or an assembly reference". I'm writing this code based on a tutorial and it looks pretty much identical to the one in the video. There weren't any errors in that code, so I'm wondering what my mistake is. :/

using UnityEngine; using System.Collections;

 public class RocksGO : MonoBehaviour {
 
     public enum rockStates
     {
         idle,
         highlighted,
         exploding
     }
 
     public rocksStates currentRockState;
 
     // Use this for initialization
     void Start () 
     {
         currentRockState = rockStates.idle;
     
     }
     
     // Update is called once per frame
     void Update () 
     {
         switch (currentRockState) {
         case rockStates.highlighted:
             Debug.Log ("Rock is highlighted.");
             break;
         case rockStates.exploding:
             Debug.Log ("Rock exploded!");
             break;
         case rockStates.idle:
             Debug.Log ("No rock selected.");
             break;
         }
     
     }
 }