ODBC, ADO, Return Value from SP problem

Hello

I need use ADODB client via ODBC. I can call stored proc
without problems. I am sure so proc is called (I am loging params)
but retern value is always null.

dim cn as new ADODB.Connection()
cn.Open("DSN=intra","nepi")
Dim cmd As New ADODB.Command
Set cmd.ActiveConnection = cn
cmd.CommandText = "testcallsp"
cmd.CommandType = adCmdStoredProc
cmd.Parameters.Referesh()
cmd.Parameters(1).Value = 22
cmd.Execute()
MsgBox cmd.Parameters(0).Value 'only null :-((

Stored Proc is simply

CREATE OR REPLACE FUNCTION testcallsp(integer) RETURNS integer AS '
BEGIN
RAISE LOG ''% '', $1;
RETURN coalesce($1,10) + 1;
END; ' LANGUAGE plpgsql;

What is wrong please?

Thank You very much
Pavel Stehule