TRy repotting ti so that it isn't pot bound.

THANKS FOR THAT-THE REASON WE LET IT STAY POT-BOUND WAS BECAUSE WE WERE TOLD IT WOULD BE MORE LIKELY TO FLOWER IF IT WAS!!!!
JUST SHOWS YOU THERE IS A LOT OF FALSE INFO AROUND!
THANKS WE WILL TRY IT

Well it is true of the Christmas cactus, which one are you asking about?

some cacti quite naturaly dont flower very often even hundreds of years .

True NP

Ours have only ever flowered when we have been away and left them shut up in our conservatory for a week. They obviously like the heat!

They vary so much we need to know what sort it is. If you don't know a photo might help. You might try soaking the pot - in the desert the plants remain dormant until it rains, and then they all burst into flower within a few days. I used to put all mine in the bath in late spring and let them stand for about five or ten minutes, and some of them responded with flower buds within the week. (I was living at home in those days and how my mother put up with this is more than I can understand now!) Make sure the pot drains thoroughly afterwards. I'm assuming that its in a well draining gritty compost. Don't do this in cold weather though, as the plant must not stay wet for more than a few days or it will rot. Make sure you don't put it in the sun if it has any water droplets on it or you will get burn marks on it. I agree that it would be a good idea to pot it on - use proper cactus compost and wear gloves!