Morphing 2 d flaps into a 3 d box?

hey guys,
i want to convert the 4 2-d flaps in to a 3 d box.

I tried morphing , but it is getting very jerky and it does not look even 10% as smooth as the morphing on this link -

HOw do i make the morph look smooth and believable? My final frame comes with a jerk.

I will truly approcieate an immediate help
REgards