To solve my problem I used BuddyAPI with the following
script. I still don't know why I couldn't get the open command to
work, but Buddy API solved my problem.
on mouseUp me
sprite(32).visible = FALSE
-- opens specified file.
-- Note you must embed budyapi extra in your projector
-- Go to the menu bar MODIFY--Moivie--Xtras and choose add
then select BuddyAPI
baOpenFile(the moviePath&"test_timeline.pdf", "Normal")