This is the mesage I get as stated in technote f915fe90.
Hang or "Failed to connect; session timed out" error when
using the fdb command-line debugger
After you start the command-line debugger for Flex, you
receive the message "Attempting to launch and connect to Player
using URL". After two minutes, a timeout message appears and
returns the error message "Failed to connect; session timed out."
The problem is usually caused by one of the following:
1. The Flash movie was not compiled with debugging on.
2. The Flash Player on your machine is not a debugger
My flash player isthe debugger version and correct. What does
it mean to "compile with debugging on" in a Flex project.