Strange behavior for iCal alarms

To run an AppleScript from an iCal alarm you do the following:

1. In Automator, create a Calendar Alarm
2. Select Utilities from the library pane
3. Select & drag Run AppleScript into the workflow area
4. Copy/paste an AppleScript into the Run AppleScript box
5. Save the newly created Calendar Alarm with name (e.g. ArchNew)
6. This will open the Automator Calendar in iCal
7. Edit the Date/Time/Repeat/...... as you want as shown in the example below

The resulting AppleScript will be stored here

/Users/<user_acct>/Library/Workflows/Applications/Calendar/ArchNew.app

Now the problem

If at a later time you want to modify the AppleScript ArchNew.app using the AppleScript Editor, it will break the binding between the iCal alarm and the AppleScript ArchNew.app

The only way I've been able to do this is delete the file

/Users/<user_acct>/Library/Workflows/Applications/Calendar/ArchNew.app

and then go back to #1 above and repeat the whole process with the modified AppleScript.

Does anyone know why the simple approach of directly editing and saving the changes to the AppleScript ArchNew.app doesn't work?