New Post: Is it possible to write text?

I'm trying to draw text in Silverlight. I blit an image and then I want to draw text on top of it

        TextBlock i = new TextBlock();
        i.Text = str;
        i.Foreground = new SolidColorBrush(color);
        wbmp.Render(i, new TranslateTransform() { X = x, Y = y });

But blitted background image is gone and text is drawn on completely black screen.
What do I do wrong? Thanks.