Need help with erasing dates in Mori

Howdy,

I'm putting together a ridiculously long applescript to sync Mori and iCal, and one nut I haven't been able to crack is the ability to erase a date value -- set it to "missing value". For instance, the script may need to remove a due date that was previously set.

Any suggestions? Script is below.

Thanks,
Mark

tell application "Mori"
tell front document
set theEntry to entry named "Buy food"
set note of theEntry to "Quickly!"
set note of theEntry to missing value
--this works
set due date of theEntry to current date
set due date of theEntry to missing value
--this doesn't
tell theEntry to store custom attribute key "Completed" value current date
tell theEntry to store custom attribute key "Completed" value missing value
--neither does this
end tell
end tell