Observation hive question
Hello all! I have a question about my observation hive. I stared it the first of Dec. from a weak nuk that I did not think would make it through the winter, the queen started laying eggs almost immediately and then 3 days later when I am expecting to see a small larva the cell is empty. I have seen the eggs but no uncapped brood. The hive is in the house near a window with a entrance, on warm days they forage and seem to do normal bee activities, but no growth. The hive is a 3 frame vertical observation hive 2 deep frames and a capped medium frame 2 frames are full of honey and pollen so I know they have ample supplies. Any ideas why they wont raise any brood?