Your original command needs an argument telling Maple which variable you are differentiating with respect to. That has nothing to do with your original error, though, which implies your parentheses are not matching up correctly. I would ask, though, what, exactly it is you are trying to solve. You have so many parentheses in there that it is confusing to try to decipher the original problem. If you are running a recent version of Maple, it might help you to right click (or ctrl-click, if you have a Mac with a one-button mouse), and scroll down within the pop-up menu to conversions, then select convert-to 2d Math input. That will show you exactly what your input would look like as an expression, rather than a complicated input line. Doing this might help you figure out your problem. (you can also edit it within the 2-d input it gives you). I just did that with your input, and the expression it gave me was understandable, aside from the fact that the differentiation symbol was missing a denominator... However, I'm not sure if the expression actually is what you were trying to input. If you have a version that supports this feature, I recommend you try it for yourself in order to make any corrections you need.

I think I see what my problem was, and I will go try to use what you've helped me to see tomorrow. Funny how the help file said almost the same thing, but left out just enough for me to get completely lost. You rock.