I was looking over the pictures I took yesterday, and examined this frame from the brown hive:
I was looking at some of the cells, and it looks like there are more than one egg in some / most of the cells. This is not good - it is the sign of a laying worker. A laying worker occurs when a hive becomes queenless, and one of the workers (which are female, but not sexually mature) all of a sudden decides to start laying eggs. Since the layer has never mated, the eggs will hatch to become drones, and the hive is doomed.
It is difficult to re-introduce a queen to a laying worker hive, since the hive thinks they have a queen, and will reject the new queen. There are some techniques to employ to try to recover a laying worker hive, but they are difficult.
I'll have to do some research to see if I can save this hive.
This also may explain why I didn't see the queen, as the laying worker is visually identical to all the other non-laying workers...