Don't stress over it. I use to find on the rare occassions I didn't lose weight I had lost inches instead. My CDC weighs and measures me every week. Sometimes the lack of pounds going off is just water retention, it is swings and roundabouts it will come off next week.
Can't stress enough how motivating it is to also see the inches come off (particularly for those weeks where you do stay the same).
Keep with it, this diet works.