IndianRingNeck.com

So i have a pair of irn's and i put in their breeding box at the top of their cage and fixed it up properly. The pair stick their head in and have a look around and climb over it but they are yet to actually go inside the breeding box,
Has anyone ever had an issue with their birds not going in the nest box?
Or have any reasons why they wouldnt want to go in?

ALso the hole is 3inch in diameter

Its my only pair at the moment actually.
But as far as i know the box is set up right and their both feeding each other and 'kissing', they dont sit together as the hen chases the male a bit but for some reason they seem hesitant to enter the nest box..