Hello,
I wanted to follow up with this thread. I ended up going with 3dMVM and renamed the subject IDs based on their group so that they wouldn't repeat (ex: sx01 became sx01LD, sx01S, sx01AB). I finally stopped getting the "rectangular" error message, and got a new one saying that the data table could not be found. I put the "@" back in front of the data table file and it worked, so I am not sure why I got the same error with and without it.
Thanks for your help!!