Load something into a scrollpane and the scrollfunction won't work?

I load a bunch of pictures into a movieclip that I use as scrollcontent in a scrollpane. All pictures are there and it looks like it should, except that the scrollbar in the scrollpane isn’t there. I guess that the scrollpane still thinks that the empty movieclip that I load all the pictures into still is empty. How can I do to fix this?