C# Problem ODBC output parameter from postgresql funtion

Hi

How i get the output parameter from the function,
is always nothing in console.
What is wrong?

Here in c#

string connstring = "DSN=PostgreSQL35W";
string procedure = "{CALL f1001.fn_check_insert_mission02(?,?)}";

OdbcConnection connection = new OdbcConnection(connstring);

OdbcCommand cmd = new OdbcCommand(procedure, connection);

cmd.CommandType = CommandType.StoredProcedure;

OdbcParameter themissionNameParam = new OdbcParameter( "@p_mission_name", OdbcType.NVarChar, 256 );
themissionNameParam.Value = "mission1";
themissionNameParam.Direction = ParameterDirection.Input;
cmd.Parameters.Add( themissionNameParam );

OdbcParameter themissionIdParam = new OdbcParameter( "@p_mission_id", OdbcType.Int);
themissionIdParam.Direction = ParameterDirection.Output;
cmd.Parameters.Add( themissionIdParam );


// Add the output parameter.

// Execute the command.
connection.Open();
cmd.ExecuteNonQuery();
connection.Close();

Console.WriteLine("New Mission has ID of " + themissionIdParam.Value);

Console.WriteLine();
Console.ReadKey();

here is the function

CREATE OR REPLACE FUNCTION f1001.fn_check_insert_mission02
(
IN p_mission_name varchar,
OUT p_mission_id integer
)
RETURNS integer AS
$$
DECLARE
v_mission_id int;

BEGIN
select mission_id into v_mission_id from f1001.mission where mission_name = p_mission_name;
if not found then
insert into f1001.mission (mission_name) values (p_mission_name) returning mission_id into v_mission_id;
end if;
p_mission_id = v_mission_id;
END;
$$
LANGUAGE 'plpgsql'
VOLATILE
CALLED ON NULL INPUT
SECURITY INVOKER
COST 100;