So in the past couple weeks, I have been making a lot of bread and pizza. I thought, "What better way to improve them, then to get a starter?" So using the Tartine(KAAP flour only) method I tried catching a culture in my kitchen. No luck

and since I have read you only catch a good sourdough 40% of the time (can anyone say whether or not this is true?) , I figured I would just buy one. I needed some Caputo and saw someone saying free sourdoughs at
www.nybakers.com, so I decided to give it a try. Wanted to get some real experience before I started spending money on sourdoughs. I was anxious to get started once it got here so I jumped in right away. Here is the process I used(following the instructions on the bottom of the starter section on the website):
Step one was to dissolve the dried sourdough in 57g of warm water, and then mix with 57g of flour. I have been using KAAP flour exclusively for the entire process.
Step two was to let it sit until it doubled. It doubled for me in about a day.
Step three, once it doubled, I added 115g of water, and 130g of flour. Again it doubled in slightly longer than a day.
Step four, Without discarding any, I added another 115g of water, and 130g of flour. Nothing happened, but it was supposed to double in around 10 hours! I tried feeding it more, but no luck!
Currently I have it split into two batches trying different things to salvage it with each. I got one of them, ever so slightly to rise since last night, but no activity in the other. A few hours after I stir them up, you can see some bubbles in them, so I am hopping there is still a chance. They each way a little less than 300g.
Any suggestions? Anything I am doing wrong? What is a good ratio, starter:flour:water, I should be feeding them in the start, after? Any ideas on if they are still alive given my descriptions? This being my first experience with sourdough, I still have tons to learn so throw any advice you can throw my way will be extremely helpful and much appreciated. Anyother questions about my processes or anything let me known.
thanks,
JJ