Loading TextAsset under different scenes

I am using TextAsset to load .txt resources into a label:

//Load text data from resources
		TextAsset toothdata = (TextAsset)Resources.Load(filename, typeof(TextAsset));
		reader = new StringReader(toothdata.text);
		
		
		//confirm if textdata is valid and read it
		if ( reader == null )
		{
   		Debug.Log(filename+".txt not found or not readable");
		}
		else
		{
   		// Read each line from the fil+string txt;
			string txt;
			longtext="";
            while ( (txt=reader.ReadLine()) != null)
            {
			longtext += txt;
	
			}
			reader.Close();
			UILabel label = NGUITools.FindInParents<UILabel>(labeltarget);
			Debug.Log (filename+".txt target found");
			//the problem is below
			label.text=longtext;// line 106
			//the problem is above
			
			Resources.UnloadAsset (toothdata);

This script is shared among different scenes. If I open a single scene it works flawless but if I move from one scene to another the script gives me the following:
NullReferenceException: Object reference not set to an instance of an object and points to line 106 (or line 25 in the script above) on that script. The problem persists even if I request text on one scene, return to the main and go back to that scene again. I am pretty sure I need to unload something but I am stuck. Any help?
Thanks

UILabel label = NGUITools.FindInParents(labeltarget);

The problem might be here. There was a “labeltarget” object in the first scene but in the second it got destroyed. If you use “DontDestroyOnLoad” on object with this script, you will have the object, but all the references within it will be dead because when scene switched, all referenced objects got destroyed.

Therefore “NGUITools.FindInParents” couldn’t find the label and therefor adressing label.text gives you the exception.