How do I access functions in Main Time line

Hey I’m fairly new to AS3. Here’s my issue.

lets say for example, on the main time line i have a function

[COLOR=RoyalBlue]function myFunction(num:Number)

[COLOR=Black]and I add a movie clip btnSm to the stage like this.

[COLOR=RoyalBlue]var btnSm:MovieClip = new BtnSmall();
and lets say inside btnSm’s timeline has an event that calls myFunction on mouse click, for example

[COLOR=RoyalBlue]var btnNumber;

this.addEventListener(MouseEvent.CLICK, gotoLink);

function gotoLink(event:MouseEvent)
and This wont work for me. I tried root.myFunction(btnNumber)
I tried MovieClip(root).myFunction(btnNumber), none would work.

[COLOR=Red]So, How can I access a function on the main timeline in AS3? [/COLOR] In AS2.0 you can do this by _root.myFunction();

appreciate your help
thank you