Movie clip depths issue

Hello everyone,

   I have a question regarding the depths of movie clips in flash. The situation is as follows: I have a main swf with manually set movie clips that act as buttons in this case; this main swf acts as a search form that once it is filled a search results window (also a movie clip from library) pops up on top of the main swf and all its buttons-clips. Now here is the thing, the new pop up window movie clip DOES obscure the form on the main swf visually, however when I go over the new window clip, the buttons of the main form that are beneath it are still detected by flash player and are NOT obscured by the new window action wise, although visually they are not seen.
   Could you please tell me what is the reason for that? How can I make the pop up movie clip obscure the contents of _root movie clip and its contents visually AND functionally.

          Thanks ahead.