RadioButtonGroup wird nicht angezeigt :-(

import java.util.ArrayList;

import tsys.activity.R;

import android.content.Context;
import android.graphics.Color;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.LinearLayout;
import android.widget.RadioButton;
import android.widget.RadioGroup;
import android.widget.TextView;

public class RadiogroupAdapter extends ArrayAdapter<Object> {
  
    RadioGroup mRadioGroup;
    TextView re;
    Context context;
    String TAG = "RGA";

      private ArrayList<Object> items;

      public RadiogroupAdapter(Context context, int textViewResourceId, ArrayList<Object> items) {
              super(context, textViewResourceId, items);
              this.context = context;
              this.items = items;
      }
      
      @Override
      public View getView(int position, View convertView, ViewGroup parent) {
              View v = convertView;
              
              if (v == null) {
                  Log.d(TAG," Layout");
                  LayoutInflater vi = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
                  v = vi.inflate(R.layout.list_items, null);
              }

              Object o = items.get(position);
              
              if (o != null) {
                  if(o instanceof String){
                      Log.d(TAG, (String)o);
                      re=((TextView)v.findViewById(R.id.listtv));
                      re.setText((CharSequence) o);
                  }
                  else if(o instanceof String[]){
                      mRadioGroup = (RadioGroup)v.findViewById(R.id.radiobuttons);
                      createRadioButtons((String[]) o);
                      Log.d(TAG, "DONE");
                  }
              }
              return v;
      }
      
      public void createRadioButtons(String[] rating)    {
          mRadioGroup = new RadioGroup(context);

          LinearLayout.LayoutParams lp = new RadioGroup.LayoutParams(
              RadioGroup.LayoutParams.WRAP_CONTENT,
              RadioGroup.LayoutParams.WRAP_CONTENT);

                for (int j = 0; j < rating.length; j++) {
                    RadioButton rb = new RadioButton(context);
                    rb.setTextColor(Color.BLACK);
                    rb.setText(rating[j]);
                    Log.d(TAG, "Rating: " +rating[j]);
                    mRadioGroup.addView(rb,0,lp);
                }
      }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="fill_parent"
    android:background="@android:color/white"
    android:orientation="vertical"
    android:weightSum="1" >
<TableRow 
    android:layout_width="match_parent"
    android:layout_height="wrap_content">
    
<TextView  xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:padding="10dp"
    android:textSize="30dp" 
    android:textColor="@android:color/black"
    android:id="@+id/listtv"
    >
</TextView>

<TableRow 
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >
<RadioGroup
        android:id="@+id/radiobuttons"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal"
        >
     </RadioGroup>
</TableRow>
</TableRow>
</LinearLayout>