Problem installing plpgsql

One of my customer unable to install plpgsql
with next message:
www2(dms)~>psql -d www -c "select tst(); "
ERROR:  Load of file /usr/local/pgsql/lib/plpgsql.so failed: dlopen
'/usr/local/pgsql/lib/plpgsql.so' failed. (/usr/local/pgsql/lib/plpgsql.so:
Undefined symbol "SPI_tuptable")
www2(dms)~>

This problem exists onlty on FreeBSD 3.1
the same sources build on 2.2.8 works properly.
what does it mean?
Env:FreeBSD www2.sptimes.ru 3.1-RELEASE FreeBSD 3.1-RELEASE #4: Tue Mar 2313:18:41MSK 1999
wplus@www2.sptimes.ru:/usr/src/sys/compile/SPTIMES i386
 
Postgres 6.4.2 release
PS:How about adding something like -a key to pg_version to report fullrelease and compile information?

---
Dmitry Samersoff, dms@wplus.net, ICQ:3161705
http://devnull.wplus.net
* there will come soft rains ...