Applescript automate double keystroke I need to emulate a keystroke using applescript for double time shift press.

Adding Part of snippet..

tell application "System Events"
    keystroke shift
    keystroke shift
end tell


Even tried 

keystroke shift
delay 0.1
keystroke shift


still doesn't work. Any ideas?
You need to key down followed by key up:

tell application "System Events"
    key down shift
    key up shift
    key down shift
    key up shift
end tell