I don't think its much of a combining thing as more of the emotions have to be balanced in your heart.
Think about it like light, you can't just combine all the colors wishywashy, because if one or two colors are not of the same intensity, then you're not going to get white, just a lighter color of the one thats more intense.
I think thats how it is with the emotions. Its definantly not the absence of these emotions, because that's what the Black Lanterns are. No I think its more that Dawn and her predecessor were completely in tune with their emotions. All of them working in harmony together. She has them all in equal levels and is able to control them to a t.
The Black Lantern rings just can't seem to grasp that. I bet that if they have their own language, peace is not a word in it...
Awesome villain.
