AppleScript: Cannot Create New Folder In Finder

Using the Script Editor, I recorded a script that creates an new folder within another folder:

tell application "Finder"
activate
make new folder at folder "my folder" of startup disk
end tell

This script records fine, but when I try to run or change it, it fails. Why?
This problem occurs If you installed the PhotoFlash Scripting Additions that came with QuickTake camera. The "Photoflash Utilities" addition defines it's own version of "Make Folder" which is different from the one the Scriptable Finder defines. This extension was defined and written before the Scriptable Finder was widely available.

In order to properly create a folder, remove the "Photoflash Utilities" from the Scripting Additions folder located in the Extensions folder.
Published Date: Feb 18, 2012