襄樊四中梁一凡:VB做的图书馆管理系统的一个问题

这是出错的代码，说是“对象关闭时,不允许操作”，调试停在这一句：If .RecordCount > 0 Then
代码如下：
Private Sub cmdSave_Click()
Dim objCopy As New Recordset
If Trim(txtNum) = "" Then
MsgBox "编号不能为空！", vbCritical, "系统用户管理"
txtNum.SetFocus
txtNum.SelStart = 0
txtNum.SelLength = Len(txtNum)
ElseIf Len(Trim(txtPWD)) <> 6 Then
MsgBox "用户口令必须为6位字符串！", vbCritical, "系统用户管理"
txtPWD.SetFocus
txtPWD.SelStart = 0
txtPWD.SelLength = Len(txtPWD)
ElseIf Not txtAuth Like "[0,1]" Then
MsgBox "用户权限代码必须位0或者1！", vbCritical, "系统用户管理"
txtAuth = ""
txtAuth.SetFocus
Else
Set odjCopy = Library_Manage.rsSysUsers.Clone
With objCopy
If .RecordCount > 0 Then
.MoveFirst
.Find "编号＝'" & Trim(txtNum) & "'"
'检查编号是否被使用
If Not .EOF And .AbsolutePosition Then
MsgBox "编号: " & Trim(txtNum) & "已被使用，请使用其他编号！", vbCritical, "系统用户管理"
txtNum.SetFocus
txtNum.SelStart = 0
txtNum.SelLength = Len(txtNum)
Exit Sub
End If
End If
End With
'保存记录
Library_Manage.rsSysUsers.Update
MsgBox "数据保存成功！", vbInformation, "系统用户管理"
cmdAdd.Enabled = True
cmdDelete.Enabled = True
isAdding = False
picNavigation.Enabled = True
End If
End Sub