PL/pgSQL Function Problem

I am trying to create a function that creates a user
and adds a row to a table.  It produces no warnings or
errors when I create the function but when I attempt
to execute it I get a syntax error.  I do not
understand why this is happening.  Any help would be
greatly appreciated.

SELECT create_author( 'name', 'username', 'password'
);

ERROR: syntax error at or near "$1" at character 14
CONTEXT: PL/pgSQL function "create_author" line 7 at
SQL statement

Here is the code:

CREATE OR REPLACE FUNCTION create_author (
VARCHAR(32), VARCHAR(32), VARCHAR(32) )
RETURNS INTEGER AS '
    DECLARE
        name_        ALIAS FOR $1;
        username_    ALIAS FOR $2;
        password_    ALIAS FOR $3;
        authorid_    INTEGER;
    BEGIN
        CREATE USER username_ WITH ENCRYPTED PASSWORD
password_ IN GROUP authors;

        INSERT INTO Authors
            ( Name, Username )
        VALUES
            ( $1, $2 );
        SELECT Max( AuthorID ) INTO authorid_ FROM Authors;

        RETURN authorid_;

    END;
' LANGUAGE 'plpgsql'
SECURITY INVOKER
RETURNS NULL ON NULL INPUT;



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