Masking a dynamic component

I created a dynamic table that shows countries and values for each country (from a text file).

That table was created with attachMovie

I want to display only a small portion of the table, so I want to mask it.

I tried using a mask in the upper layer but then it didnt display the data.

Note: [COLOR=green]The move hierarchy is: _root > component Table > Movie Clip Table > (Script which create the table).[/COLOR]

¿Is there any way to do it by Actionscript? (or other way).

Thanks in advance,