Have to agree with everybody's comments about cereal. 30g is more like 1 (stuffed) handful - but have little hands! I was having 60g and my old mechanical scales weighed it as 40g, so for weeks I was having an extra 300 calories weekly, just from cereal!
There are plenty of reasons why you may not be losing weight - first of all, bear in mind it's a new way of eating for you and your body may be just be in shock with it being the first week. But here are a few other things it might be (shamelessly copy pasted from what I wrote to Laura Jayne's post):
1. Bloat - are you drinking enough water? too much sodium in your diet?
2. Constipation - are you er, regular. Eating enough roughage?
3. Hormones - we women can start retaining water upto 2 weeks before Aunt Flo actually visits
4. Change in routine? Doing extra exercise can initially make you gain weight as your muscles swell and retain water. Plus, you look denser with 1lb of muscle than 1lb of fat!
5. Kind of related to number 4 - you may have lost body fat, which isn't measured on normal scales
6. Foodwise - look at what you're eating and see if it's as healthy as it can be. I'm believer that somebody eating 1200 healthy calories will be healthier and probably do better long term than somebody eating 1200 calories that incorporates a lot of "diet" or "faddy" foods that don't fill them up (and can prompt an eventual trip off the wagon!). I'm not saying never have chocolate or a glass of wine but see what substitutions you can make.
7. Make sure you are weighing everything you eat that isn't pre-packaged, preferably on digital scales. You will be amazed how we can estimate wrongly - it's been a real eyeopener for me since Sunday alone when I bought my new kitchen scales!