Newbie pasta maker: What did I do wrong?

After making pasta at InTavola Cooking Academy in Florence on our trip to Italy last fall I decided I HAD to learn how to make my own, it was so good. Santa got me a pasta maker attachment for our Kitchen Aid mixer, and my first batch of linguine (using a recipe I found on Love & Lemons) was okay, but a little tough. I figured it was because I used all-purpose flour.

I decided to try the recipe we used at InTavola and bought some 00 white flour and Semola, both made by Caputo, and tried again. (The flour was fresh, according to the expiration dates.) The dough was unusable. It was so dry while I was mixing it a quarter of the flour wouldn't mix in, so I added a little oil, and it was still too dry. Then I wet my fingertips a couple of times, and finally was able to incorporate most of the flour. Total knead time was at least 10 minutes. It never got "shaggy," but more like PlayDoh. But after resting it was very hard, and either went through the widest pasta rollers with great difficulty or not at all. In sum, it was a lost cause.

What did I do wrong? Here's the recipe:

• 100 grams (3/4 cup) 00 flour
• 100 grams semolina (I used semola)
• 2 large eggs
• salt

The recipe didn't say how much salt. I used about a quarter teaspoon, maybe less. I mixed the salt thoroughly into the flour before I mounded it. Is that what I did wrong? Afterwards I saw the recipes said to add the salt to the depression in the flour. Maybe the salt reacts with the eggs before they get incorporated into the flour?

I bake bread all the time, and the pasta I made in Florence came out great, so I don't think it's my technique. And as I said, the L&L batch came out okay, just a little tough. Maybe the recipe I have from InTavola missed an ingredient? But I've seen similar recipes elsewhere.

Any wisdom appreciated!