how to control one movieclip from another?

I have 2 movieclips on the stage. When i get to a certain frame in one movieclip, I want it to tell the other movieclip to stop. How do I do this? Let's call them mc_1 and mc_2. On frame 10 of mc_1 I was trying to call:

MovieClip(this.parent.mc_2).stop();

but I get an error that says "1119: Access of possibly undefined property mc_2 through a reference with static type flash.display:DisplayObjectContainer."

Both movieclips are on the stage in the same frame. Can someone help? This should be simple but I don't know what I'm doing wrong.

MovieClip(parent.getChildByName("mc_2")).stop();

That worked great. Thanks, cancerinform!!!

This is very interesting and something I have been thinking about. Can you explain this a little further? Would this work with buttons? I have about 5 buttons aligned side by side each other. Then I have a tab which is a movieclip. I would l would like the tab to slide back and forth on top of each button when the appropriate button is selected.
Here is my inspiration. http://www.htc.com

I've already created the buttons and the tab movieclip. I'm just not sure how to arrange this and what the actionscript would look like. I'm using AS3.

I'd appreciate any information, advice or resources you could offer. thanks!

The way that probably works is that one button is sliding over the other buttons and the text changes. You can only use a movieclip as a button to do this.

So are you saying that one could not control a movieclip from a button? If it is possible I guess what I'm looking for is... if the button is clicked have the separate mc go to frame x.

I'm not too woried about the text in the example, mainly just getting the tab to move across the screen when the button is clicked. thanks!

You can control a movieclip from a button of course. But the sliding button has to be a movieclip to control the textfield inside.

good. :) What would the AS3 script look like to achieve this effect? I guess that the part I really need help with. I'm not sure what the code would look like. Can you post an example? When this button is clicked the movieclip goes to X frame. Thanks for replying and your assistance.