调用 'LJ_TEST' 时参数个数或类型错误
本人属于刚开始学习存储过程的菜鸟一枚，现遇到这个问题解决不了，求大神指教：
我的存储过程是：
create or replace procedure lj_test(inparam in varchar2,  outparam  out varchar2, inoutparam  in out varchar2)
as
  varparam varchar2(28);
begin
  varparam := inparam;
  outparam := varparam || inoutparam;
end;

调用的C#程序是：
conn.Open();
                OracleCommand cmd = new OracleCommand("LJ_TEST", conn);
                cmd.CommandType = CommandType.StoredProcedure;

                OracleParameter[] parameters ={
                                                  new OracleParameter("inparam",OracleType.VarChar),
                                                  new OracleParameter("outparam",OracleType.VarChar),
                                                  new OracleParameter("inoutparam",OracleType.VarChar,28)
                                              };
                parameters[0].Value = "dd";
                parameters[2].Value ="ff";
                parameters[0].Direction = ParameterDirection.Input;
                parameters[1].Direction = ParameterDirection.Output;
                parameters[2].Direction = ParameterDirection.InputOutput;