VB.Net实现用户登录

下面的是我的代码：
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim conn_err As Integer
Try
Me.ViekyTableAdapter.Fill(Me.VbstudyDataSet.Vieky)
Catch ex As Exception
Me.lblMessage.Text = ex.Message
Me.lblMessage.BackColor = Color.Red
conn_err = 1
End Try
If conn_err = 0 Then
Me.lblMessage.Text = ""
Me.lblMessage.BackColor = Color.LightGreen
End If
End Sub

Private Sub btnLogin_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLogin.Click
Dim un As String
Dim pw As String
un = Me.txtUserName.Text
pw = Me.txtPassword.Text
If un = "" Then
MsgBox("用户名输入为空。请输入！", MsgBoxStyle.OkOnly, "出错咯 - -!")
ElseIf pw = "" Then
MsgBox("密码输入为空。请输入！", MsgBoxStyle.OkOnly, "出错咯 - -!")
Else
Dim i As Integer
For i = 0 To Me.VbstudyDataSet.Vieky.Rows.Count - 1
If Me.VbstudyDataSet.Vieky.Rows(i)("uid") = un Then
MsgBox("用户名检测完成")
End If
Next
End If

程序数据库连接正常，但运行后，以下这段没反应
If Me.VbstudyDataSet.Vieky.Rows(i)("uid") = un Then
MsgBox("用户名检测完成")
End If
希望高手指出不足和如何修改，谢谢！