Watch the numbers. They are messed up in this pattern. The Rib Pattern stitch says it’s a multiple of 2 sts +1 st but it’s really 3 sts plus 1 stitch. This throws off the cast on numbers as well as the increase numbers on the last row of ribbing.

There is a lot of errata with this pattern. Even though it’s an easy knit, you have to have some knowledge of knitting to catch it all. Almost every section of the pattern has something wrong with it.