Hmm I see nothing wrong in your code and dont see why you think you need to use [1], but maybe you wanted a crossOver() of the price instead of just comparing it? Your comparing will enter trades all the time on every bar, but crossover only enters it when the price crosses over the border.
Using the [1] will compare the previous value of the DChannel rather than the current one which by necessity will have risen or fallen in line with the price and therefore will never be exceeded.
The trade count criteria prevent multiple trades being opened.
