I have 2 hives, one is going unbelievably strong. The other not so good though it appears healthy.
In the weak hive I dug into the brood boxes and found the queen. She seems energetic and healthy however I can't seem to find brood anywhere. It appears that the existing bee population is healthy, they are eating the sugar water I am providing, but they are not building out comb in some of the new frames. They just seem to be hanging out???
Should I requeen now or wait a little longer?
One benefit to having multiple hives is that you can "Robin Hood" them. That is, take some frames of whatever you need from the strong one and switch them with the weak.
Just don't over do it, or you will end up with two weak hives.
By providing the weak hive with a frame containing eggs from the strong hive, the bees will be able to produce a new queen (superceedure) if they aren't content with the one they have.
Another thing to check for is disease or parasites (i.e. Varroa mites) in the weak hive. Try to determine why they are weak. It may or may not be the queen.
How is the weather doing there? is it raining and cool most of the time, or are the bees able to fly and collect nectar?
Possible reasons she's not laying:
She has failed and has no fertile eggs to lay.
The population of workers isn't high enough to care for the brood.
She's a virgin from a supercedure or emergency and hasn't started to lay lay. If the queen dies it takes up to 28 days from that time until you see eggs. Even longer until you see larvae.
You could do what Wayacoyote says, and give them a frame of brood. That way they have the resources to resolve the problem themselves. Come back in seven days and see if you see eggs or larvae on any other frames than the one you gave them.
If you don't have a frame of brood then check in seven days for eggs and larvae and if there are none, get a queen from somewhere or kill the old queen, combine this one for now and do a split later.