Hi Alan,
Do I understand that you are feeding them a pigeon food? If so, this is a big problem. African Greys have very different nutritional needs than pigeons. Without proper nutrition, a hen will not lay eggs. Your birds should be on a nutritionally balanced diet for parrots, such as pellets or our foraging diets, as 80% of their daily diet. In addition you can offer dark leafy greens, fresh veggies and some fruits as 20% of their diet. They need to be converted to this diet and eating it well for at least 6 months before you give them a nest box, so remove the box for now. Once you hang the nest box, you can offer an egg food daily – this can be a commercial dry egg food, or cooked eggs with the shell washed, crushed and cooked with the eggs. Feed this while she is preparing to lay eggs, and while she is feeding chicks. Your birds also need to be old enough – at least 5-7 years old. Hopefully making change in their diet will help.
Thank you for asking Lafeber,
Brenda