Cloning oddity

[David Squance]

I have a script which stops on one step which involves cloning a card.
There's no error message.  The same script works fine to a certain point,
cloning other cards, but when it reaches a certain one, won't go any
further.  The standalone (OS X, same as development) works fine.  I tried
running it in the IDE with suppressing (or is it suspending) the
development environment, but I had to force quit Rev.  Any suggestions?