ActionScript 2.0 :: Passing Arguments To Function?

I have a movie clip that contains several movie clips, only one of which should be shown at a time. Which one is shown, depends on what buttons the user selects.Having trouble with the syntax for passing the argument in a button to the function that controls the tweening of the clips. (When I hard code the references into the function, it works, so I know the basic function is ok).There's a clip called 'slide1_mc' which contains various MC's to be shown based on user selection (in this case, using 'system' clip as the first one already showing). Here's the code in the parent clip of that item:

Code:
var currSection = slide1_mc.system_mc;
function changeSection(newSection):Void {
TweenLite.to(currSection,.3,{_yscale:200, _xscale:200, _alpha:0});

[code]....

Here's one of serveral buttons that will control the content to be seen:

The code in the button is:

Code:
var changer = slide1_mc.software_mc;
smallButton.onPress = function() {
_parent.changeSection(changer);
};

So - the initial part of my function works so I know my 'external' initializing of "currSection" is working (that clip is zooming/fading out)... but then the clip that I want to fade in isn't doing anything.