The scene with the text doesn't look liike it has any transparency, so when you Alpha Over it on another image, it completely covers that image. Change Alpha to Transparent under Shading in the Render tab. Change this only on the scene named Scene in your file. Scene.001 and Scene.002, which contain the halos, should keep the default setting, Sky. The halos really do get rendered, but they are so faint, that they're just not visible enough without a background.
You can also set them all to transparent and insert a second Alpha Over node like this, to be able to contro, the background colour.