ActionScript 2.0 :: Using String Parameter In Function For Mc Path

I've got a problem with a function i'm using to dynamically move movieclips around - its like this at the mo:

function wjump(number) {
_root.content.aboutus.webwizard.targetY = startPos[number];
}

where startPos is an array with numbers.

I want it to be like this:

function jump(target, number) {
target.targetY = startPos[number];
}

so any clip can be moved as long as it has a targetY variable. But it won't work for some reason. Is there some sort of special syntax i should use like [] brackets? I tried this around the target in function body but it did not work.