iTunes artwork problems

The following script worked when I first ran it (it’s not mine, I found it elsewhere), but I now get an AS NSCannotCreateScriptCommandError error. By running it from Script Editor, and viewing the Event Log, I’ve narrowed it down to the section where the script is trying to get the data from the track’s artwork. The script is a rating script (1 of 5) for rating iTunes songs via QS hotkeys. Here’s the script:


[This script was automatically tagged for color coded syntax by Convert Script to Markup Code]

Note that there is the commented out section for passing the notification task to QuickSilver–running the script either way results in the same error, just from the respective app. (Actally scripting is broken in the latest beta of QS, but that’s besides the point) Can someone please help me figure out why AS is unable to properly parse the artwork data? Like I said, this script worked as is before, and now it doesn’t. I’m not sure what, if any, updates or upgrades broke it, but it’s definitely broken now.
TIA!

Oh, and here’s the output from the Event Log in Script Editor:

tell application "System Events"
	count every application process whose name = "GrowlHelperApp"
		1
end tell
tell application "GrowlHelperApp"
	register as application "iTunes ratings" all notifications {"Ratings"} default notifications {"Ratings"} icon of application "iTunes"
end tell
tell application "iTunes"
	get class of current track
		file track
	get current track
		file track id 1142 of library playlist id 965 of source id 48
	set rating of file track id 1142 of library playlist id 965 of source id 48 to 100
	get name of file track id 1142 of library playlist id 965 of source id 48
		"Home"
	get rating of file track id 1142 of library playlist id 965 of source id 48
		100
	get class of file track id 1142 of library playlist id 965 of source id 48
		file track
	get album of file track id 1142 of library playlist id 965 of source id 48
		"12 Stones"
	get artist of file track id 1142 of library playlist id 965 of source id 48
		"12 Stones"
	exists every artwork of file track id 1142 of library playlist id 965 of source id 48
		true
	get data of artwork 1 of file track id 1142 of library playlist id 965 of source id 48
		«data PICTBC7200000000012C0
<<<SNIPPED ALOT>>>
0736565207468697320706963747572652E000000FF»
		"GrowlHelperApp got an error: NSCannotCreateScriptCommandError"

TTT