Flash 8 - OnRollOver on nested MovieClips

Hello there
I am using Flash 8 and have this problem.
I have a movieclip image called X. Moreover I have another movieclip called Y inside of X. Y covers just part of the total area of X. Both X and Y have defined the onRollOver funtion. The behaviour should be like this: when I put the mouse over X, then the X animation starts and when it ends it shows the movieclip Y in its last frame in which it stops. Now, if I don’t get the mouse out of the area covered by X and furthermore, I put the mouse over the area covered by Y, I was expecting that the onRollOver function in Y was called. Nevertheless, Y is not called.
Does anyone how to fix this?
Thanks.

buttons inside buttons don’t work.

you would have to define an area, that when the mouse goes into, it activates x, then then x finishs Y is a button.

if you follow me