ERROR: translation failed from server encoding to wchar_t

I am using tsearch2 with pgsql 8.2.5 and get the following error when
calling to_tsvector :
"translation failed from server encoding to wchar_t"

My database is UTF8 encoded and the data sent to to_tsvector comes
from a bytea column converted to text with
encode(COLUMN, 'escape').


In 8.1 with tsearch2 it worked perfectly ...


Thanks for you help,

ilan