Capital asset sales worksheet help

I sold some stock that I had for many years. It was held in E*TRADE and I imported the 1099B directly into my Turbo Tax Premier. When I do a smart review, I get errors saying adjustment amount must have a value when an adjustment code (other than C, M, or T is entered). Code N has been entered. What value do I put in the highlighted box? Do I even need to fill it in?