Leaking Nappies

I purchased Huggies Dry Comfort and the nappies is leaking. I change my daughter every 4 hours but by the time I want to change her, her clothes are soaked in wee. The lifeguards doesn't seem to prevent leakages. She's wearing size 4 because she weighs 10kg and this number is from 8-14 kgs. I'm rather disappointed as this is not the first time this happened to me.