AppleScript error -10006

I need a little help. I get an error while running this script:

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with timeout of 10 seconds

tell application "Finder"

activate

duplicate file "DO NOT REMOVE.rtf" of folder "File Backups" of disk "Macintosh HD" to folder "DO NOT REMOVE" of disk "Time Machine" replacing yes

end tell

end timeout

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the error message I receive is:

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error "Finder got an error: Can’t set folder \"DO NOT REMOVE\" of disk \"Time Machine\" to disk \"Time Machine\"." number -10006 from folder "DO NOT REMOVE" of disk "Time Machine"

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I cannot find any information on this error type. I'm running Mac OS X 10.8.2.

Thanks.