Syntac error

Hello,

I've defined the following function and get an syntac error whle compiling.
Whats the fault?

CREATE FUNCTION "myscheme"."authenticate" () RETURNS
"pg_catalog"."refcursor" AS
$body$
DECLARE
    curAccessRights refcursor;

BEGIN
    OPEN curAccessRights FOR
        SELECT * from myscheme."tblUsers";

    RETURN curAccessRights;
END;
$body$
LANGUAGE 'sql'

Regards Timo