Training, all mixxed up

I've been trying some new things with my indoor trainer season this year. (the indoor trainer season started earlier than normal due to my shoulder injury) For the last week or so I've had a rough time completing my workouts at the prescribed wattage output. Then today after another workout in which I was unable to meet the correct power I set out to figure out why. Then I found it was a very simple problem with my math. When I was figuring out the power output for my steady state intervals I figured out my workout range 10 watts too high. Now 10 watts isn't much but it changes the workout completely. Hopefully now things can get back on track. I was just working too hard during the intervals and not allowing myself enough time to recover before the next hard set.