Your iris need to be divided; it is recommended to do so every three to four years. Do a search here in Gardenweb, I am sure there are several threads or even a FAQ in the Iris forum explaining how to do it.

Are they planted too deep? They like their rhizomes to get sunlight. Do they get a half of day of sunshine?

Mine bloomed last year, then I divided them in the fall and they haven't blomed this year. Does dividing them cause a lapse in blooming?

I have read that dividing them can cause a lapse in blooming, as the new divisions are not mature enough to produce flowers yet.