Sourdough Starter Failure!!

I have been wanting to do this for years!  I love sourdough bread and it is both hard to find and expensive here.  Tescos does a nice white loaf, but it currently costs £1.79.  I think that I can make my own which will be healthier, cheaper, organic, and not too difficult.  I already use my bread machine a fair bit because I have arthritis which makes kneading dough difficult for me.  The AGA is also really unreliable in that it cooks unevenly and you can't control the temperature.  So, although AGAs are known to be great for baking, mine definitely is not!  I hope this starter will add a new and healthy dimension to my breadmaking.

In researching how to make sourdough starters I have found dozens of different versions.  I have settled on one I found from Hubpages.

You will need:

Organic rye flour
Organic bread flour (I am using spelt)
water
bowl
plastic wrap

Day 1  Mix together one cup of whole wheat or rye flour with 3/4 cup of water.  Make sure all of the dough is wet.  It should make a ball.  Keep in a clean bowl and cover with plastic wrap.  Leave at room temperature for one whole day.  (Mine was more wet and did not make a ball.  Most of the recipes I read said to make a soupy mixture, so let's hope this works out ok!)
Day 2  Mix together one cup of bread flour with 1/2 cup of water.  Add this to the bowl and mix well.  The mixture may be softer, without any rise.  Cover again and leave for another day.  (I used rye again.  Hope this is ok!)
Day 3  Mix 1 cup of bread flour and 1/2 cup of water.  Discard half of yesterday's dough.  Mix in the new mixture.  Cover and leave again.  It should be rising a little by now.
Day 4  Repeat Day 3.  Wait a few hours until the dough has doubled.  Take one cup of starter and mix with 3 1/2 cups of bread flour and 2 cups of water.  Mix and cover with plastic.  After 6 hours it will have doubled and become bubbly.  You can now use this starter in a recipe. 

Store this starter in the fridge.  It should last forever with proper feeding.  Feed the starter every three days and every time you use it.  (If you use it every 2-3 days for breads, pancakes, etc this should be easy).  To feed, take away half of the culture and mix in equal flour and water in a 3/2 ratio.

OK, so this worked really well on days one, two and three.  Then on day four I followed the directions and waited for it to bubble up.  And waited and waited overnight because it was getting late.

And nothing.  Now I have had a look on the Internet for other recipes and guidance.  I can only guess as to what has gone wrong.  I think there are a few possibilities.  Firstly, I used organic rye flour on days one and two, then organic spelt flour on days three and four.  Not sure if this is that big a deal really.  Secondly, I used a metal spoon to stir on days three and four.  This did not affect the mix on day three, but could well have done by day four.  (I read that you should avoid using metal after the fact).  And thirdly, although it was a warm day, my kitchen was suddenly much colder on the fourth day.  And apparently the starter needs to have a fairly warm temp to get going. 

So fortunately flour is cheap and I have enough to have another go.  I am now trying to decide which methods and which flour to use, because there are so many!  Rye is supposed to work very well, so I will likely stick with it.  So here I go again.