My budgies are not breeding!

Question
Hi,
 I bought 3 pairs of budgies about 2 years back. Six months later, I added nest-boxes (terracotta pots that are commonly used as nesting boxes here in India). But they refused to mate and breed.
 A friend suggested that I cover the cage on all sides except the front. Which I did, but that did not induce them. So on some other people's advice I have made them a huge cage 4'(length)x2'(width)x7'(height). I also added 4 more pairs of birds. I have a 50:50 male:female ratio. It has been 3 weeks hence.
  I find a few of the bonding. 2 females seem to be in breeding mood with a brown cere. Some males have been chasing these females, but they do not seem to wanna let the males get onto them. Looks like the males are trying to induce the females, but females are just running away and no mating is taking place. The females are also not going into the nest boxes in the new cage.
  I feed them a regular diet of millets, grass (with seeds), coriander leaves, basil leaves, Greens with seeds etc. I tried fruits but they refused to eat.
  Am I not getting something right? Would you be able to help me please?  

Answer
Hello Bala Somu,
The only thing I can suggest is patience. They will breed. And as long as every pair has a nesting "pot" or "box" they will breed. A shortage of boxes will cause fighting and none of the birds to breed.

The females and males must feel 100% certain that if they breed, it will be for the benefit of their young.

Good Luck!