findclientbyname("spartan").player.mountObject(findclientbyname("asdf"), 0));
What is this extra right-hand parentheses here for? Try removing it. That should clear stuff up.
Just so you don't het some 5 pages of an essay telling me I'm wrong, here's the technique. You start at 0. for every left parentheses, you add 1. for every right parentheses, you subtract 1. When done counting the parentheses, you should get 0. Your snippet of code turned out with -1, as shown by the extra right parentheses.
Man, I say parentheses alot.
Anyway, I hope this helps!