PDO调用存储过程获取返回参数的问题

[xpfoo2010]

存储过程代码
------------------------------------------------------------------------------------------------------------------------------

create procedure p_login (
    in _name varchar(30),
    in _pwd varchar(30),
    out _StaffID int ,
    out _FISManager int,
    out i int)
    begin

      set i =(select count(*) from t_staff where FName=_name and FPwd=_pwd);
      if i=0 then 
         set _StaffID=(select FStaffID from t_staff where FName=_name and FPwd=_pwd);
         set _FISManager=(select FISManager from t_staff where FName=_name and FPwd=_pwd);
       else
         set _StaffID=0,_FISManager=0;
      end if;
     end

PHP代码
-----------------------------------------------------------------------------------------------------------------------------

  $result=$pdo->prepare("call p_login(?,?,?,?,?)");
  $result->bindParam(1,$_POST["tbName"]);
  $result->bindParam(2,$_POST["tbPwd"]);
  $result->bindParam(3,$StaffID,PDO::PARAM_INT,11);
  $result->bindParam(4,$ISManger,PDO::PARAM_INT,11);
  $result->bindParam(5,$i,PDO::PARAM_INT,11);
  
  if ($result->execute())
      echo $StaffID;
    else
	  print_r($result->errorInfo());

结果
-------------------------------------------------------------------------
Array ( [0] => 42000 [1] => 1414 [2] => OUT or INOUT argument 3 for routine my_crm.p_login is not a variable or NEW pseudo-variable in BEFORE trigger )
感觉PHP对存储过程输入输出参数支持力度有些吃力，求大神帮忙看一下问题出在哪里？

[xpfoo2010]

自己搞定

  $result=$pdo->prepare("call p_login(?,?,@StaffID,@ISManger,@i)");
  $result->bindParam(1,$_POST["tbName"]);
  $result->bindParam(2,$_POST["tbPwd"]);
  //$result->bindParam(3,$StaffID,PDO::PARAM_INT,11);
  //$result->bindParam(4,$ISManger,PDO::PARAM_INT,11);
  //$result->bindParam(5,$i,PDO::PARAM_INT,11);
  
      if($result->execute()){
		  $rs = $pdo->query("select @StaffID,@ISManger,@i")->fetch(PDO::FETCH_ASSOC);  
		  print_r($rs["@ISManger"]);
		  }
		else {
		  print_r($result->errorInfo());
		}