Here is that round's instructions:
Starting with 160 stitches; Knit 54 sts to 1st marker. Slip marker, ssk and k to 2 sts before 2nd marker, k2tog. Slip marker, k 54 sts to 3rd marker. Slip marker, ssk, knit to 2 sts before BOR marker, k2tog. After each descrease round you will have two stitches less between the markers. For example, after this round you will have 156 sts total.
As I typed it, it occured to me that the error was in reading the pattern. Perhaps I should only do 1 ssk at a time, not as I did originally which was 'ssk and knit' up until 2 sts before a marker. Thanks for any advice.