function length(numeric) does not exist

Version: PostgreSQL 9.2.6, compiled by Visual C++ build 1600, 32-bit

When I try to use the function length occurs the error:

"ERRO: 42883: função length(numeric) não existe" (function length(numeric)
does not exist).

Then I try to create length function:

CREATE OR REPLACE FUNCTION length(tsvector)

RETURNS int4 AS

'$libdir/tsearch2', 'tsvector_length'

LANGUAGE 'c' IMMUTABLE STRICT;

ALTER FUNCTION length(tsvector) OWNER TO postgres;

But the return is:

----------------------------------------------------------------------------
----------------------------------------------------------------------------
--------

ERRO: não pôde encontrar função "tsvector_length" no arquivo "C:/Program
Files/PostgreSQL/9.2/lib/tsearch2.dll"

(could not find function "tsvector_length" in the file "C:/Program
Files/PostgreSQL/9.2/lib/tsearch2.dll")

********** Error **********

ERRO: não pôde encontrar função "tsvector_length" no arquivo "C:/Program
Files/PostgreSQL/9.2/lib/tsearch2.dll"

(could not find function "tsvector_length" in the file "C:/Program
Files/PostgreSQL/9.2/lib/tsearch2.dll")

SQL state: 42883

----------------------------------------------------------------------------
----------------------------------------------------------------------------
--------

I need the help!

Thanks!