My first batch was a Northern Brewer American Amber Ale extract kit, I had some problems on bottling day and I'm sure I got some oxidation and then my capper broke 15 bottles in and I had to put a lid on it and wait for a few days until they sent me a new capper. The first 15 bottles didn't carbonate very well and the first few of the rest of the batch doesn't seem to be carbonated at all. I've done 3 batches since and they all seem to be carbing great.