Polish Sourdough - 1.1

I followed the recipe exactly this time and it was a complete failure - not even a hint of sourness. For 1.2 I am going to feed and warm the little beastie until it goes off. And if that doesn't work I'll make it with milk and leave it on a radiator until the whole place stinks. I've also bought some rye flour to try, though I suspect that will only affect the texture and consistency.