Yoghurt (yogurt?) with Milk-powder

Have been experimenting with making Yoghurt out of milk powder.

My first tries were pretty unsuccessful and after the third generation started to have an unpleasant smell. A bit of colleagual consultation and the cause was identified as not keeping everything sterile. So moral here is to pour lots of hot water over everything you use - including any utensils, jars etc..

Uses commercial yoghurt maker (1Kg)

1. Make the starter batch with easy-yo or similar. Prefer sugar free Low fat or Greek (Greek has full cream milk)
2. Before you dish up the made yoghurt sterilise the spoon and take a spoon full and put it into a sterilised jar (this will be your starter for the next batch)
3. .. eat the Yoghurt
4.  When empty clean/wash out the yoghurt jar (I use the dishwasher). 
5. Now to make the next batch
6. Sterilise everything (Spoons, jars, etc)
7. Add saved starter to jar
8. Add 1 1/2 cups milk powder to mix. (I like to combine 1 full cream and 1/2 trim - gives it more of a greek texture)
9. Proceed to make yoghurt as normal
10. For next batches repeat from Step 2.

Notes: Find best time to make it is after dinner in the evening and leave it overnight so its ready in the morning,