Transition problem

hey i’m new to using the transition manager in as 3.0. and when i run my code i get an error message. one transition works, but the second one doesn’t. when you click the “about” button to go to the about us section, i get this:

TypeError: Error #1009: Cannot access a property or method of a null object reference.
at fl.transitions::TransitionManager/saveContentAppearance()
at fl.transitions::TransitionManager/set content()
at fl.transitions::TransitionManager$iinit()
at myFirstFlashSite_fla::MainTimeline/myFirstFlashSite_fla::frame2()

in the output window and the transition doesn’t work.

here’s a zip file of my project. it’s not that big, just too big to upload directly to here. just follow the link and click on “free user” option when you download.

it’s probably a pretty easy fix, but i’m new to actionscript, so any help would be appreciated.