ขอความช่วยเหลือเรื่อง VB ครับ หัดใหม่ครับติดที่ index Out Of Range Exception Was Unhandled

Imports System.Data.SqlClient
Public Class frmlogin
    Private Sub timer1_tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        lbclock.Text = Date.Now
    End Sub

    Private Sub frmlogin_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim strconnection As String = "data source=.\SQLEXPRESS;AttachDbFilename=C:\Users\COM\Documents\icedata.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True"
        Dim strSQL As String = "SELECT user,pw From user_id"
        Dim cn As New SqlConnection(strconnection)
        Dim cm As New SqlCommand(strSQL, cn)
        Dim dr As SqlDataReader
        cn.Open()
        dr = cm.ExecuteReader()

        Do While dr.Read()
            Dim strrow As String = dr.Item("user").ToString() & ControlChars.Tab & dr.Item("pw").ToString()   ///มันบอกว่าบรรทัดนี้มีปัญหาครับ
            lstuserid.Items.Add(strrow)
        Loop
        dr.Close()
        cn.Close()
    End Sub

    Private Sub GroupBox1_Enter(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles gblog.Enter

    End Sub

    Private Sub txtuser_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles txtuser.TextChanged

    End Sub


    Private Sub lbclock_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lbclock.Click

    End Sub

    Private Function strrow() As Object
        Throw New NotImplementedException
    End Function

End Class