Unable to call functions defined in XML2 contrib

Hi All,
I am running PostgreSQL 8.4 offered with OpenSUSE 11.2. It works
exceptionally well. I have installed the contrib package in order to use
the functions provided by XML2/pg_xml as explained in this page:
http://www.postgresql.org/docs/8.4/static/xml2.html
However, when I try to run this SQL command:
SELECT * FROM

xpath_table('id','xml','test',
'/doc/@num|/doc/line/@num|/doc/line/a|/doc/line/b|/doc/line/c',
'true')
AS t(id int4, doc_num varchar(10), line_num varchar(10), val1 int4, val2 int4, val3 int4)
WHERE id = 1 ORDER BY doc_num, line_num

It returns an error saying that:

ERROR: function xpath_table(unknown, unknown, unknown, unknown,
unknown) does not exist
LINE 2: xpath_table('id','xml','test',
^
HINT: *No function matches the given name and argument types. You might
need to add explicit type casts.*

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

ERROR: function xpath_table(unknown, unknown, unknown, unknown, unknown)
does not exist
SQL state: 42883
Hint: No function matches the given name and argument types. You might
need to add explicit type casts.
Character: 21

Don't know what is wrong.
I am anxiously waiting for your reply.
Franclin.