It appears that I cannot build successfully using the Debian versions of the libdb* libraries. My workaround was to install Berkeley DB from
www.sleepycat.com (as suggested in the INSTALL notes) in /opt. I then changed my DB_PREFIX to point to the appropriate location, did a "make clean" and then a "make".
If anyone suspects why I wasn't able to build Ice using the Debian libdb libraries I'd be very happy to know.
Regards.