ADODB.Command 异常 '800a0bb9' 参数类型不正确，或不在可以接受的范围之内，或与其他参数冲突 _ASP

ADODB.Command 错误 '800a0bb9' 参数类型不正确，或不在可以接受的范围之内，或与其他参数冲突。
浏览器错误提示：
ADODB.Command 错误 '800a0bb9'
参数类型不正确，或不在可以接受的范围之内，或与其他参数冲突。
/admin/user_qx.asp，行 35
（注：代码中红色部分即35行）

网页界面：

服务器行为：

网页代码：
<%@LANGUAGE="VBSCRIPT" CODEPAGE="65001"%>

<%
Dim MM_editAction
MM_editAction = CStr(Request.ServerVariables("SCRIPT_NAME"))
If (Request.QueryString <> "") Then
  MM_editAction = MM_editAction & "?" & Server.HTMLEncode(Request.QueryString)
End If

' boolean to abort record edit
Dim MM_abortEdit
MM_abortEdit = false
%>
<%
' IIf implementation
Function MM_IIf(condition, ifTrue, ifFalse)
  If condition = "" Then
    MM_IIf = ifFalse
  Else
    MM_IIf = ifTrue
  End If
End Function
%>
<%
If (CStr(Request("MM_update")) = "form1") Then
  If (Not MM_abortEdit) Then
    ' execute the update
    Dim MM_editCmd

    Set MM_editCmd = Server.CreateObject ("ADODB.Command")
    MM_editCmd.ActiveConnection = MM_busi_conn_STRING
    MM_editCmd.CommandText = "UPDATE [user] SET [class] = ? WHERE username = ?"
    MM_editCmd.Prepared = true
    MM_editCmd.Parameters.Append MM_editCmd.CreateParameter("param1", 5, 1, -1, MM_IIF(Request.Form("qx"), Request.Form("qx"), null)) ' adDouble
    MM_editCmd.Parameters.Append MM_editCmd.CreateParameter("param2", -1, 1, -1, MM_IIF(Request.Form("MM_recordId"), Request.Form("MM_recordId"), null)) ' N/A
    MM_editCmd.Execute
    MM_editCmd.ActiveConnection.Close

    ' append the query string to the redirect URL
    Dim MM_editRedirectUrl
    MM_editRedirectUrl = "showUser.asp"
    If (Request.QueryString <> "") Then
      If (InStr(1, MM_editRedirectUrl, "?", vbTextCompare) = 0) Then
        MM_editRedirectUrl = MM_editRedirectUrl & "?" & Request.QueryString
      Else
        MM_editRedirectUrl = MM_editRedirectUrl & "&" & Request.QueryString
      End If
    End If
    Response.Redirect(MM_editRedirectUrl)
  End If
End If
%>
<%
Dim Recordset1__MMColParam
Recordset1__MMColParam = "1"
If (Request.QueryString("u") <> "") Then
  Recordset1__MMColParam = Request.QueryString("u")
End If
%>
<%
Dim Recordset1
Dim Recordset1_cmd
Dim Recordset1_numRows

Set Recordset1_cmd = Server.CreateObject ("ADODB.Command")
Recordset1_cmd.ActiveConnection = MM_busi_conn_STRING
Recordset1_cmd.CommandText = "SELECT * FROM user WHERE username = ?"
Recordset1_cmd.Prepared = true
Recordset1_cmd.Parameters.Append Recordset1_cmd.CreateParameter("param1", 200, 1, 20, Recordset1__MMColParam) ' adVarChar

Set Recordset1 = Recordset1_cmd.Execute
Recordset1_numRows = 0
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>

<body>
<p>修改会员<%= Request.QueryString("u") %>的权限</p>
<form id="form1" name="form1" method="POST" action="<%=MM_editAction%>">
  <p>
    <label>
      <input type="radio" name="qx" value="1" id="qx" />
      管理员</label>
    <br />
    <label>
      <input type="radio" name="qx" value="0" id="qx" />
      普通会员</label>
  </p>
  <p>
    <label>
    <input type="submit" name="button" id="button" value="提交" />