Duh!
It worked! I did have to re-thread the loom, though. The first time I threaded, I used the treadling profile which turned out to be different from the threading profile. That's why the blocks wound up in different places from what I intended. So, in the photo, on the right, you see the correct weave. The one on the left, while not all that bad, is just not what I had intended. My error stemmed from the fact that I did not graph out the weave structure completely enough to see the differences.
The other problem is that I could not get the blocks to be square. I smooshed the bejeebers out of the weft threads & they just would not pack down. So, next time, I'll try a sett of 18 epi instead of 20 epi. I am using 9.75/3 cotton for warp and weft tabby, and 6/2 cotton for pattern weft.
This weaving class (Intermediate Weaving taught by Sondra Rose) was awesome. I learned not only many new weave structures, but really put my Louet Delta countermarche loom through its paces. There are so many more things to try now! In the meantime, though, I've gotta get caught up on the laundry. . .