what does the queens brood pattern look like. If you are feeding is the hive getting honey bound and got no room to lay. Sounds like there may have been a possiblity of swarming. has the weather been hot and or a dearth on queens will slow down durring these time since the hive doesnt need the numbers. A lot of time queens get blammed for things out of there control and get the axe only to have another queen introduced that will have the same problem. Before you requeen you need to find out exactly why they are not building.