Sieve vacation function not working..

[Joseph Silverman]

ALL other sieve functions work as described.  Vacation simply doesn't  
work - mail is delivered, but no response is sent out.  This is true  
in multiple versions of cyrus:

* OK HOST Cyrus IMAP4 v2.2.13-Mandriva-RPM-2.2.13-4mdv2007.1 server  
ready
* OK HOST Cyrus IMAP4 v2.2.12-Mandriva-RPM-2.2.12-15mdk server ready

The one "caveat" is that we are using sendmail as our MTA.  I have  
tested many sieve functions, they all seem to work except vacation.   
And, yes, I always use a different from address to avoid the send- 
once-every-n-days function.

Is there something I am missing?  Obviously vacation works for some  
folks out there.  But just as obviously, from googling for failures,  
there are a substantial number of folks who can't or couldn't at the  
time the messages were posted, get it to work.

Thank you for your time! - Yossie

Here are a few googled links reporting issues with sieve/vacation in  
cyrus:

http://archives.devshed.com/forums/networking-100/cyrus-sieve-with- 
vacation-does-not-go-1673174.html
http://www.usenet.com/newsgroups/comp.mail.imap/msg00608.html
http://www.webservertalk.com/archive202-2006-6-1548266.html
http://www.irbs.net/internet/info-cyrus/0412/0031.html
http://forums.fedoraforum.org/archive/index.php/t-20225.html