Applescript to type text, followed by a modifier key combo? I want to use TextExpander to activate when I type the specific text "attached", and have the AppleScript type out the word "attached" (since TextExpander will remove it), and then invoke the keystroke Control-Z

I can get each to work individually, but not together. Here is the code I am using based off of code I found here:

    tell application "System Events"
    keystroke "attached"
    keystroke "z" using control down
    end tell
I'm not sure what the TextExpander application name and process name is so I will guess what it is. 

activate application "TextExpander"
    tell application "System Events"
        tell process "TextExpander"
            keystroke "attached"
            delay 0.5
            keystroke "z" using {command down}
        end tell
    end tell