Component problems

I’m having some annoying problems when using components in my flash files. Examples are Scrollpane, Checkboxes, Dropdown lists.

When I make a new file and set one up, it works. Simple.

When I make one (or one copy across) inside my master document it simply does not work. I just get a white box where the compenent is positioned.

Are there any known issues with clashing instances / names / clips?