Load and unload image with MovieClipLoader

Hi all
I can´t solve this problem:

I need to have in my presentation 2 btns, one btn will remove the loaded
image and second load unloaded image again.
Please can you look at my example file, I spend some hours about this,
made lot of test but I don´t know how to write code for those 2 buttons.
The problem ist to call those buttons from root (main scene - timeline)
if I have the loaded image on other timeline.

Thanks for any help.

Here ist the prepared example F8 file: http://www.bresco.cz/test/setmask.zip