Scarce of flowers

I inherited this Christmas cactus from a friend a few years ago. Each year it has produced half a dozen flowers. Last spring I repotted it in proper cactus compost. It loved the bigger pot and doubled in size, So now it has two flowers. TWO! Any helpful advice would be gratefully received. I gave the other plant  I inherited from the same friend to my son. It is covered in flowers every year. Bah. The flowers are very beautiful though, see the extra.