Problem with encoding conversions

Hi All,
I try to migrate a database from WIN1251 to UTF8 but
I have a problem dumping from WIN1251 to UTF8.

pg_dump -C -E 'UTF8' a > a_utf8.sql
pg_dump: SQL command failed
pg_dump: Error message from server: ERROR: could not load library
"/usr/local/lib/postgresql/utf8_and_cyrillic.so": dlopen
(/usr/local/lib/postgresql/utf8_and_cyrillic.so) failed:
/usr/local/lib/postgresql/utf8_and_cyrillic.so: Undefined symbol
"check_encoding_conversion_args"
pg_dump: The command was: SET client_encoding='UTF8'

$psql --help
This is psql 8.1.16, the PostgreSQL interactive terminal.

a=#SELECT version();
version
-------------------------------------------------------------------------------------------------
PostgreSQL 8.1.15 on i386-portbld-freebsd6.4, compiled by GCC cc (GCC)
3.4.6 [FreeBSD] 20060305
(1 row)

a=# \l
List of databases
Name | Owner | Encoding
-------------------+---------+----------
a | kaloyan | WIN1251

Could you please suggest what to do. I try to Google for a solution but
nothing appears.

Thanks in advance.

Kaloyan