Scene's movieclip not found on as3.0

Hi
I’ve got a stage in which I load different swf as menus or sections

main
|-menu
|-section
| |-menu
… …

In this main swf and others I put some movieclips directly to the screen [drag&drop from the library] call them as… ‘link_mc’ and move, scale, change them through this main swf class document

The menu one has an ‘image_mc’ movieclip on the screen. It compiles correctly but when compiling ‘section’ I get:
1120: Access of undefined property img_mc.

If i declare this img_mc on the menu document class I get this other error
1151: A conflict exists with definition img_mc in namespace internal.

menu also gives me other problems, like crashing when loading 2 menus

So have you got any idea about what should I do?