Making yogurt

I realised that one way we generate a lot of waste is by eating so much yogurt. First I stopped buying those little six or twelve packs and just stuck to the kilo cartons but I'm not so sure there is any economy there as it still tends to get all eaten at one sitting!
I thought I'd give making yogurt a go. I had a look online and there were tons of people saying how easy, cheap and delicious making your own yogurt is. It's a fairly simple process, making it from scratch: you boil some milk (to kill any nasties in it) then let it cool to blood temp, add some starter culture (other yogurt), and then keep it at blood temp for 8 hours or so. Fiddly, but essentially simple, right? There is a contraption out there that is supposed to make yogurt making Easi (geddit?), and I managed to procure one of these from the Freecycle list (have I explained Freecycle before? you can list things you want to get rid of that are too much hassle to sell but too good to throw out. you can also ask for things - I asked for the Easi-Yo as I figured it was the sort of thing people would have sitting in the back of their cupboard).
First I tried to make yogurt from scratch as described above, using the Easi-You to maintain the temp as required. It didn't turn into yogurt. Fine, perhaps I didn't let the milk cool enough, or maybe the starter yogurt didn't actually have any live cultures, whatever. I tried again. Still no good.
Then I bought the sachets of yogurt starter from Easi-Yo. These are pretty foolproof - add water, shake, put in the contraption (basically a big thermos) with boiling water around. Easy, right? Well, I got yogurt. But it was sour. I snuck it into smoothies and things but there is no way you could eat it straight. I tried this a couple of times, always sour. Then I wised up and figured maybe there were some bad bugs living in the plastic container you make it in. So a good scrub, and soak in vinegar. In the meantime Nicole gave me a whole bunch of the starter sachets she had at home (yes, she's one of those with a EY sitting in the back of the cupboard!).
So these, I can't get to work either. One time I got something that was kind of like cottage cheese, another time I got essentially just a lot of greenish whey. At least they're not sour. The sachets are just out of date (early April?) but you wouldn't really think that would make a huge amount of difference, right? Sure it's live cultures in there, but they're freeze-dried or something. A couple of weeks isn't going to make much difference, surely.
I can't believe that I, master of following instructions and cooking stuff, can't even make yogurt! However, I will bravely soldier on. I won't let ten or so failed attempts stop me. One day, I will make my own yogurt, and it will be DELICIOUS!!