Why do my cockatiels lay infertile eggs

[Iluvcockatiels]

I have 3 pairs of cockatiels, they seem to be well bonded, and I've seen them "doing it", so why do they keep laying infertile eggs???
My 3 hens are all sitting on eggs, I actually removed 14 eggs from one box yesterday much to the disgust of one of my hens who got very upset, I have to remove the eggs from the other nest boxes as well but worried they will just go straight back in a lay again, any ideas!!!

[Birdman]

Hello and sorry for the delay. How long have your hens been laying infertile eggs? Hopefully they are becoming accustomed to the nesting environment and shall soon be breeding naturally. Most hens will throw out their infertile eggs soon enough. As you say the act of copulation is underway and it is unlikely that all three males are infertile so we suggest that you keep providing them with plenty of nutrients, cuttlefish, shell grit, broccoli or thistle weeds and you can add cockatiel/small parrot crumbles (available from most pet shops). Business should be booming in near time!