Back to Where I Started

I was so happy that I was able to finish the back of the sweater on Friday night. It's just about done blocking. I eagerly started the front and when I was about 40 rows into it, I realized that I had done something completely wrong. The ribbing in between the cables was only showing three knit columns instead of four. At first I just kept going, but then I realized the placket would get screwed up. So I had no other choice but to rip everything out and start all over again from the beginning. Yesterday I caught up to where I had been before I started frogging. The directions said to continue the front as for the back and so, I had started my row with a P1, when it should have been a K1, which was printed. I just didn't see it!