Autoresponder problem

I'm having difficulty with an error in a procmail autoresonder
recipe.  This is identical to one that I've had working on my
own account, but doesn't seem to want to work when implemented
for someone else.

The recipe is identical with the "complain" recipe from
SpamBouncer and the autoresponder/vacation examples in
procmailex (with obvious differences about handling
the To: header).  Whenever this recipe executes I get
a "sh error (2) unexpected end of file" on the line
that pipes the response to sendmail:

   | $SENDMAIL -oi -t

Any ideas what might cause this particular error?
I'm going crazy here!!!!!

Dave Stone