How to include script in Assets Bundle ?

hii all..

I want to load scripts in assets bundle which is component of the gameobject..

But i failed to load those scripts. I have read the documnets given : http://docs.unity3d.com/Manual/scriptsinassetbundles.html

I have tried this like :

  //www = WWW.LoadFromCacheOrDownload ("file://E:/HTML5 Testcase/New Unity Project/Resources.unity3d", 1);
         www = WWW.LoadFromCacheOrDownload ("localpath/sample.unity3d", 1);
         
         // Wait for download to complete
         yield return www;
 
         if(www.error != null)
         {
             Debug.Log(www.error);
             yield break;
         }
 
         if(www.error != null)
         {
             throw new UnityException("WWW download had an error : " + download.error);
         }
 
         // Load and retrieve the AssetBundle
         AssetBundle bundle1 = www.assetBundle;
         bundle1.LoadAllAssets();
 
         // Load the TextAsset object
         TextAsset txt = bundle1.LoadAsset("Assembly-CSharp.dll", typeof(TextAsset)) as TextAsset;
         Debug.Log ("Txt : " + txt);
 
         if( txt!= null )
         {
             // Load the assembly and get a type (class) from it
             var assembly = System.Reflection.Assembly.Load(txt.bytes);
             var type = assembly.GetType("MyClassDerivedFromMonoBehaviour");
             
             //Instantiate a GameObject and add a component with the loaded class
             GameObject go = new GameObject();
             go.AddComponent(type);
             Debug.Log("Loaded.. ");
         }

But txt is coming null.

What is the problem with this script. please help me guys.

Thanks.