AppleScript failes to launch a program

Question

Hey there,
I'm trying to activate the programm SelfControl automatically at given times via iCal. I'm doing that by scheduling an event in iCal which linkes then to an Automator script. Everything is working fine as long as I have the program SelfControl opened before launching the script. As soon as the program is not running during the activation by iCal the script is not working. Can anyone tell me what I'm doing wrong?
Here my script:
on run argv
          set defaultTime to 15
          try
                    set myTime to item 1 of argv as number
          on error
                    set myTime to defaultTime
          end try
          tell application "Usable Keychain Scripting"
                    tell current keychain
                              set myPass to (password of first generic item ¬
                                        whose name contains "SelfControl")
                              -- eliminate invisible characters, or "gremlins," from password
                              set x to quoted form of myPass
                              set myPass to do shell script "echo " & x & " | perl -pe 's/[^[:print:]]//g'"
                    end tell
          end tell
          tell application "SelfControl" to launch
          tell application "System Events"
                    tell process "SelfControl"
                              tell slider of window "SelfControl" to set value to myTime
                              click button "Start" of window "SelfControl"
                    end tell
                    tell window 1 of process "SecurityAgent"
                              with timeout of 15 seconds
                                        repeat
                                                  set tryAgain to false
                                                  try
                                                            set value of text field 2 of scroll area 1 of group 1 to myPass
                                                  on error
                                                            delay 1
                                                            set tryAgain to true
                                                  end try
                                                  if not tryAgain then exit repeat
                                        end repeat
                                        click button 2 of group 2
                              end timeout
                    end tell
          end tell
end run
Plus the errors I get from running the script without having opened SelfControl before:
I repeat: Everything is working fine, as long as I have "SelfControl" opened manually before running the script!
Thx in advance for any help.

Answer 1

This sounds like a typical race condition... you're telling System Events to target the application before it's had a chance to actually launch.
You can try adding a delay after you launch the application to give it time to load, or you can add a check to ensure the target window exists before trying to make changes.