Aviary pic

Picture of my aviary curently housing 4 pairs of pekin robins and one pair of mesia and single mesia in one pen. Having some Issues with the mesia pair, last year she laid eggs off the perch with no nest built at all, this year they built a nest and she laid eggs in it but broke 2 out of 3 one by one. Any advice would be appreciated, i believe the male might be way ahead of the female but i will listen to any other ideas on why this is happening. Also why would only 2 pairs of pekins build nest out of 4 proven pair when i am doing everything the same, have few years of keeping/ breeding pekins and they keep suprizing me with new challenges. 

Hi Florin, I'm guessing the total length is around 40ft? Is that split into sections with a pair of Pekins in each or is the whole length one flight?
My Bulbuls broke their eggs regularly last year, very frustrating. This year i have increased their calcium in the water and had no issues with the hen breaking the eggs.

Good eye, yes the aviary is 40’x12’ split into 6 equal pens and one narrow but full lenght at the end with a safety corridor. Not sure what i can do better with the mesia i am open to any suggestions.

  Here is a pic of the safety corridor and feeding drawers and pen doors.

We’re also having problems with our Mesia pair this year but they are in a different aviary. Stopped sitting twice but they are sitting again now but it’s only been a week so far so will have to see how it goes.
They look in excellent condition just seem to take a while to settle.