Yea but him and Kirk are right and yes do use hot mud (setting type ) for first and even 2nd coat then you can top with the lite weight. One of you problems was the lite weight the "lighter" the mud the less strength it has. That is why when you get to things like lite , ultra lite, and topping you shouldn't use any of these to fill or tape. What they are basically for is your finish coat, they are lite so they will fill small imperfections easily, and they are easy to sand. Now back to the OP corner bead is a place where you need max. strength because it is always getting bumped or hit, or if it is on a window opening think of what happens when you open that window time after time after time. And a lot of hangers still use nails in bead because nail heads are a lot easier to cover than screw heads. Hope this helps.