Professional :: Make A Movieclip And Import It To Another Fla File?

I am having one of those 'self doubt sanity' moments. Entering melt down here ! I want to make a movieclip from a graphic map background, and some existing movieClips that reside in another .fla
 
In this other .fla file the movieclips are in the wrong layer so by starting over I wish to tidy things up.
 
How do I create a movie clip from such ?
 
Then I start thinking, how does one create a movie clip, then bring it into another file ?
 
I even did a test that went:-

1) create new AS3 file

2) draw a box

3) select box and hit F8 Convert to symbol, select movieclip and name it box_movieclip

4) d/click box and made a classic tween and had box moving across stage.

5) save as and named file MovieClip_Boxtest.fla

6) open new file AS3 and import to library the BoxTween.fla  and got a message saying One or more files not imported as problems reading them.
 
So having done the above stages 1 to 5 which made a movieclip, how do I get that into another fla file ?