messages not being scanned by uvscan

[Patel, Anjana]

I'm running MailScanner 4.26.8-1 on RedHat 7.3 and McAfee engine v4.2.40

I recently upgraded our three mail gateways to the latest version of
MailScanner and two are working ok but for some reason the third is not
scanning for viruses (spam checking is working ok).  The configuration
on all three is the same apart from spamassassin.  The other two are
running 2.60 and the problem system is running 2.61. 

I've not used symbolic links in MailScanner.conf or in
virus.scanners.conf

uvscan --version reports the following:

Virus Scan for Linux v4.24.0
Copyright (c) 1992-2003 Networks Associates Technology Inc. All rights
reserved.
(408) 988-3832  LICENSED COPY - Jan 27 2003

Scan engine v4.2.40 for Linux.
Virus data file v4326 created Feb 18 2004
Scanning for 86216 viruses, trojans and variants.

If I manually scan an infected file using the wrapper command it finds
the virus.

There are no errors in the maillog file to indicate any problems but
I've sent viruses through and they pass undetected.  Is there some
debugging I can set up to try and find the problem?

Thanks
Anjana