asp调用存储过程，提示未提供参数的错误

存储过程如下：
set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go


ALTER PROCEDURE [dbo].[GetNextLandID]
@Uid Int,
@InLandID Int,
@OutLandID Int output,
@ThisNumber Int output,
@NextNumber Int output

AS
Begin

SELECT @OutLandID=ISNULL(Min(LandID),-1) from tb_Land
WHERE Uid=@Uid AND LandID>@InLandID

IF @OutLandID=-1
SELECT @OutLandID=Min(LandID) from tb_Land
WHERE Uid=@Uid

SELECT @ThisNumber=Count(LandID) from tb_Land
WHERE Uid=@Uid AND LandID <=@InLandID

SELECT @NextNumber=Count(LandID) from tb_Land
WHERE Uid=@Uid AND LandID <=@OutLandID

Return
End

ASP调用存储过程如下：

DIM OutLandID
DIM ThisNumber
DIM NextNumber
UId=FUId
InLandID=LandID
Set MyComm = Server.CreateObject("ADODB.Command")
MyComm.ActiveConnection = MyConStr 'MyConStr是数据库连接字串
MyComm.CommandText = "GetNextLandID" '指定存储过程名
MyComm.CommandType = 4 '表明这是一个存储过程
MyComm.Prepared = true '要求将SQL命令先行编译
'声明参数
MyComm.Parameters.append MyComm.CreateParameter("@UId",3,1,4,UId)
MyComm.Parameters.append MyComm.CreateParameter("@InLandID",3,1,4,InLandID)
MyComm.Parameters.append MyComm.CreateParam