Instantiate GameObject in unity

This part of script works in editor, but in WindowsPlayer get Object reference error, can anybody help?

 WWW download= new WWW ("URL"); yield return download;
 
 AssetBundleCreateRequest assetBundleCreateRequest = AssetBundle.CreateFromMemory(download.bytes); yield return assetBundleCreateRequest;
 
 AssetBundle assetBundle = assetBundleCreateRequest.assetBundle; yield return assetBundle;
 
 try {     GameObject go = Instantiate(assetBundle.Load("objectName",typeof(GameObject))) as GameObject; } catch(Exception e) {     ErrorLoger.Log(e.ToString()); }