Trouble using variable to get mc property

Question

I'm creating a rollover effect for a collection of 12 mcs so
that on mouseover the clip grows a little bit. This involves
locating the x and y coordinates each clip, and to do so I've tried
to farm the job out to a few variables and one function, so that
the onRollOver event simply sets the variables and calls the
function.
It's not working. Flash seems to be implying that I can't use
a variable (string type) to get a property -- ie. variable._x
rather than myInstanceName._x
Is this correct, or is my error elsewhere?
Hope you can help.
(By the way, there will of course be an onRollOut event as
well. Just getting this bit to work first.)
Thanks;
Rick
(Here's the code):

Answer 1

When using brackets to do what you are doing can be
frustrating if you are not aware on how to use them especially when
you start nested movieclips. Below I have several variations on
ways to do it and ways not to do it. I am using a variable ( i ) to
show how it is done by dynamically referencing a movieclip. My
rule-of-thumb are the following when using brackets ( [ ] );
1. Encapsulate ONLY ONE movieclip with brackets.
2. Never have a dot next to the outer left bracket.
3. Always have a dot next to the outer right bracket when
accessing a movieclip’s property.
For the first part of code I have a movieclip on stage with
an instance name of “ball3_mc”. For the second part of
the code I have a movieclip named “ballholder_mc” that
now contains ‘ball3_mc’ inside of it. I hope this
helps.