小弟是个新手，最近在学习，想自己实验制作一个登录程序，但ACCESS数据库和连接写好代码后，就是登录不成功，想请教一下是什么原因，以下是我的代码：
Public Class user
    Inherits System.Windows.Forms.Form
    Public MyCnn As ADODB.Connection
    Public MyRs As ADODB.Recordset
    public strcnn as string
    Private Sub okbtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles okbtn.Click
        Dim i As Integer
        Dim Username, Userpwd As String
        Dim flag As Boolean
        flag = False

        Username = Me.userbox.Text
        Userpwd = Me.pwdbox.Text

        MyCnn = New ADODB.Connection
        MyRs = New ADODB.Recordset

        strcnn = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=d:\conmuser\user.mdb"
        MyCnn.Open(strcnn)
        MyRs.Open("select * from use", MyCnn, ADODB.LockTypeEnum.adLockUnspecified, ADODB.LockTypeEnum.adLockUnspecified)
        MyRs.MoveFirst()

        For i = 0 To MyRs.RecordCount - 1
            If Username = MyRs.Fields(1).Value Then
                If Userpwd = MyRs.Fields(2).Value Then
                    MessageBox.Show("登录成功")
                    flag = True
                    Exit For

                End If
            End If
            MyRs.MoveNext()
        Next

        If Not flag Then
            MessageBox.Show("登录失败")
        Else
            Dim f As mainfrom
            f = New mainfrom
            f.Show()
            Me.Hide()
        End If

    End Sub

ACCESS数据库里字段只有两个，一个为ACCOUNT和PASSWORD。请教为什么登录程序提示登录失败？

谢谢，我晚上去试一下！