imapsieve: failed to read mailbox attribute

Hello all,

Hopefully this is something fairly simple.

I've been trying to set up the Sieve Antispam system as detailed at https://wiki2.dovecot.org/HowTo/AntispamWithSieve, but at the moment, whenever I change mailboxes I get the following message logged:

Aug 22 09:30:45 remy dovecot: imap(darac@darac.org.uk): Error: imapsieve: mailbox INBOX: Failed to read /shared/imapsieve/script mailbox attribute

and my script does not run when I move files between folders.

My sieve files are chmod'ed 0644 and the shell script used to pipe into spamassassin is 0755, so it *should* work, shouldn't it? Is there something I've missed?

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