Problems: loaded SWF cannot add movie from library

Hi!

I have a “Main” swf, which loads “Site” swf.

“Site” is a normal movie, with it’s Document Class. When I run it alone, it works fine, adding a movieclip from library into it’s stage.

But when I run “Main”, it show me an error: 1180: Call to a possibly undefined method mcSiteInside.
“mcSiteInside” is a Movieclip, from Site’s Library.