Is there any error in the log? I don't see a reason this shouldn't work.
There were problems like this that were caused by a flashplayer security patch. See https://groups.google.com/forum/?fromgroups=#!topic/livecycle/ZRj27vcLXOI
My memory is a bit hazy on this, as it was three years ago.
There was a LiveCycle blog on this November 11, 2008
Flash Player 10 broke the Reader Extensions sample application included with LiveCycle ES 8.0.1, and 8.2.1. When you use it, it will essentially hang. The workaround is to revert back to Flash Player 9 on those machines you use as LiveCycle clients.
This problem has been fixed in LC 8.2.1 SP3 as well as in ES2.
The key is to either upgrade your server or downgrade to an earlier (9) version of the flash player. (copying from the google group)
As you said, this issue is due to the changes in security in flash
player 10. The Reader Extensions webUI leverages flex. For LiveCycle
8.2.1, the file dialog automatically pops up after conversion is
complete. However, in flash player 10, there were changes to how file
reference are is handled. Since it is possible to pop up a file
dialog based on user action), and automatically poping up that file
dialog based on the old code base will no longer work. This is a
known issue in LC ES 8.2.1, and downgrading to flash player 9 works.
However, in fix pack 2 of LiveCycle ES Update 1. (18.104.22.168), this bug
on flash player 10 has been resolved with an explicit button to
download the file.
Thanks, Chuck. After I downgrade the flash palyer, it works fine.