applescript/quickeys problem

This may be more of a QuicKeys problem then applescript but I don’t know what to do to debug this. I have a Unix script that contains the following command:

osascript -e 'tell application "QuicKeys"' -e 'play shortcut named "Stop 4D Client"' -e 'end tell'

When I execute this from a terminal command line, it works flawlessly. However, when it is executed without a terminal, from a background job, the first QuicKeys command (switch to a specific application) fails (cannot switch to application). This happens even though the specific application is already the active one. Can someone give me some suggestions for debugging this? TIA.