OnListItemClick de ListActivity no funciona

En mi aplicación con ListActivity el sobrescrito onListItemClick la devolución de llamada no se activa al hacer clic en un ListView ít.

He definido una vista de lista personalizada con los siguientes archivos xml, allowinview.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/btn_Apply"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/btn_apply"
            android:onClick="onApplyClick" />

        <Button
            android:id="@+id/btn_install"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/btn_install"
            android:onClick="onInstallClick" />

        <Button
            android:id="@+id/btn_cancel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Cancel" />

    </LinearLayout>

    <ListView android:id="@android:id/list" 
            android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:focusable="false">

    </ListView>  
</LinearLayout>

y el diseño del elemento de vista checkable.xml :

  <?xml version="1.0" encoding="utf-8"?>
  <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content" >


   <ImageView android:id="@+id/img" android:layout_width="wrap_content"
        android:layout_height="wrap_content" android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" android:layout_alignParentBottom="true"
        android:src="@drawable/ic_launcher" android:focusable="false" />

    <CheckBox
        android:id="@+id/check"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
       android:layout_alignParentRight="true"
        android:layout_marginLeft="4px"
    android:layout_marginRight="10px"

    android:clickable="true">

 </CheckBox>

    <TextView
        android:id="@+id/label"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:layout_toRightOf="@+id/img"
        android:gravity="bottom"
        android:text="@+id/label"
        android:textSize="15px"/>
</RelativeLayout>

El definido ArrayAdapter se define como sigue:

     public class InteractiveArrayAdapter extends ArrayAdapter<Model> {


    private final List<Model> list;
    private final Activity context;
    private boolean changeable;

    public InteractiveArrayAdapter(Activity context, List<Model> list, boolean changeable) {
        super(context, R.layout.checkable, list);
        this.context = context;
        this.list = list;
        this.changeable = changeable;
    }

    static class ViewHolder {
        protected TextView text;
        protected CheckBox checkbox;
        protected ImageView image;
        protected int pos;
    }

    public View getView(int position, View convertView, ViewGroup parent) {
        View view = null;
        if (convertView == null) {
            LayoutInflater inflater = context.getLayoutInflater();
                view = inflater.inflate(R.layout.checkable, null);


            final ViewHolder viewHolder = new ViewHolder();
            viewHolder.text = (TextView) view.findViewById(R.id.label);
            viewHolder.checkbox = (CheckBox) view.findViewById(R.id.check);
            viewHolder.image = (ImageView) view.findViewById(R.id.img);
            viewHolder.pos = position;


            view.setClickable(true);

            if (!changeable)viewHolder.checkbox.setEnabled(false);


            viewHolder.checkbox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {



                public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                    Model element = (Model) viewHolder.checkbox.getTag();

                    element.setActive(buttonView.isChecked());
                }

            }
            );



            view.setTag(viewHolder);
            viewHolder.checkbox.setTag(list.get(position));

        } else {
            view = convertView;
            ((ViewHolder) view.getTag()).checkbox.setTag(list.get(position));

        }
        ViewHolder holder = (ViewHolder) view.getTag();
        holder.text.setText(list.get(position).showPermission());
        holder.checkbox.setChecked(list.get(position).isActive());

        if (list.get(position).isRedundant()) {
            holder.image.setImageDrawable(context.getResources().getDrawable(R.drawable.warning));
        } else {
            holder.image.setImageDrawable(context.getResources().getDrawable(R.drawable.ok));
        }
        return view;

    }

}

En la clase que extiende ListActivity, un ArrayAdapter definido se llena con un arrayList en un asyncTask (la información de la lista se calcula en doInBackground() método):

public class PermissionViewActivity extends ListActivity {

    private final static String TAG = "PMA";
    ...
     @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.permissionview);
        ...
    }

    ... 

     private class CurrentPermissions extends AsyncTask<String, Integer, String> {

        private ListActivity la;
        private Context context;



        private int progress = 0;

        public CurrentPermissions(ListActivity la) {
            this.la = la;
            this.context = la;

        }

        protected void onPreExecute() {
        ...

        protected void onPostExecute(String result) {
          adapter = new InteractiveArrayAdapter(la, permissionList, changeable);
          la.setListAdapter(adapter);
          /output with number of listitems
              System.out.println("DEBUG1 " + la.getListAdapter().getCount());
        }
     }
      ...
      @Override
      protected void onListItemClick(ListView l,  View view, int position, long id) {
        super.onListItemClick(l, view, position, id);
        System.out.println("clicked !");
      }
      ...
    }

La onListItemClick el método no se ejecuta. Al definir onClickListener en ArrayAdapter, el evento de clic funciona:

 view.setOnClickListener(new OnClickListener() {
                public void onClick(View v) {

                    System.out.println("Klick D1 " + list.get(viewHolder.pos));

                }

            });

¿Por qué funciona la definición del evento de clic en ArrayAdapter, pero no sobrescribir en ListActivity? no encuentro el fallo