TabHost setBackgroundResource yields blank tabs

I'm using:

intent = new Intent().setClass(this,MoreActivityGroup.class);

    // Initialize a TabSpec for each tab and add it to the TabHost
    spec = tabHost.newTabSpec("more").setIndicator("").setContent(intent);
    tabHost.addTab(spec);
    for(int i=0;i<tabHost.getTabWidget().getChildCount();i++)
    {
        tabHost.getTabWidget().getChildAt(i).setBackgroundResource(R.drawable.tab_feed_unselected_mdpi);
        tabHost.getTa开发者_开发知识库bWidget().getChildAt(i).invalidate();

    }

But all my tabs are blank, with just a little grey box at the bottom. Why does this not work? My goal is to have complete custom tabs without any of Android's default graphics

---

   ImageView selTab = (ImageView) tabHost.getTabWidget().getChildTabViewAt(sel).findViewById(R.id.single_tab_img);

   selTab.setImageResource(selected_img[sel]);

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Check this tutorial, it was very useful to me and I have 100% customed tabs: http://ondrejcermak.info/en/programovani/custom-tabs-in-android-tutorial/