loading asset bundle function

I was originally hard coded in loading asset bundles and the list of asset bundles started get larger, so I want to make a function that takes in some information and loads the asset bundle for me, but for some reason on the IPhone loads the last asset bundle I feed to the function but none of the others works. On the android it never gets past

www = new WWW(string path); yield return www;

since this all works if I put all the calls in the same function I assume it has something to do with all of them being in their own StartCoroutine calls. here's the function.

 private IEnumerator loadAssetBundle(string fileName, string typeName, int index)
 {
     if(Application.platform == RuntimePlatform.IPhonePlayer)
     {
         System.String strPath = "file://" +  Application.dataPath + "/../assetbundles/" + fileName;
         www = new WWW(strPath);
         Debug.Log(strPath);
         yield return www; 
         AssetBundleRequest request = www.assetBundle.LoadAsync(typeName, typeof(GameObject));
         Debug.Log(typeName);
         yield return request;
         
         _items[index] = request.asset;
         
         if(_items[index] == null)
             Debug.Log(typeName + " has gone wrong in loading prefabs");
         else
         {
             Debug.Log(typeName + " went fine loading prefabs");
         
             Debug.Log(_items[(int)eItemType.OVEN_BASE].name);
         }
     }
     else if(Application.platform == RuntimePlatform.Android)
     {
         System.String strPath = "jar:file://" +  Application.dataPath + "!/assets/" + fileName;
         www = new WWW(strPath);
         Debug.Log(strPath);
         yield return www; 
         Debug.Log(it never gets past www creation);
         AssetBundleRequest request = www.assetBundle.LoadAsync(typeName, typeof(GameObject));
         Debug.Log(typeName);
         yield return request;
         
         _items[index] = request.asset;
         
         if(_items[index] == null)
             Debug.Log( typeName + " has gone wrong in loading prefabs );
         else
             Debug.Log(typeName + " went fine loading prefabs);
     }
     else
     {
         Debug.Log("enters loadAssetBundle unity editor");
         _items[index] = Resources.LoadAssetAtPath("Assets/Zombie/AstroAssets/Resources/" + typeName + ".prefab", typeof(GameObject));
     }
 }

and I just call it like this with the appropriate fileName, typeNames and indexes(copy and pasted from the working versions

startcouroutine(loadAssetBundle(fileName,typeName,index))

startcouroutine(loadAssetBundle(fileName,typeName,index))

startcouroutine(loadAssetBundle(fileName,typeName,index))

startcouroutine(loadAssetBundle(fileName,typeName,index))