求助，菜菜菜菜鸟

Private Sub 登录_Click()
Dim strpassword, strusername As String
Dim flag As Integer
Dim record As ADODB.Recordset
flag = 0
record.Open "select*from 用户表", record   此处报错 91 对象变量或with块变量未设置
Do Until record.EOF
strusername = record("用户姓名")
strpassword = record("用户密码")
If UCase(Me.用户姓名.Value) <> UCase(strusername) Then
record.MoveNext
Else
flag = 1
Exit Do
End If
Loop
If flag = 0 Then
MsgBox "该用户不存在，请重新输入"
Me.用户密码.Value = ""
Me.用户姓名.Value = ""
Me.用户姓名.SetFocus
登录.Enabled = False
Exit Sub
Else
If UCase(Me.用户密码.Value) <> UCase(strpassword) Then
MsgBox ("密码错误，请重新输入")
Me.用户密码.Value = ""
Me.用户密码.SetFocus
登录.Enabled = False
Exit Sub
End If
End If
Do登录页面.Close
Do登录页面.OpenForm "主界面"
End Sub