รบกวนผู้รู้ทีนะคะ ติดเออเร่อค่ะ ไม่รู้ว่าเพราะอะไรและจะแก้ไขยังไงดี

Imports System.Data
Imports System.Data.SqlServerCe
Imports System.Data.SqlTypes
Imports System.Drawing
Imports System.ComponentModel
Imports System.Windows.Forms
Public Class ProductAdd
    Dim strID As String = ""
    Public Property _strID() As String
        Get
            Return strID
        End Get
        Set(ByVal value As String)
            strID = value
        End Set
    End Property
    Private Sub ProductAdd_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim reader As SqlCeDataReader
        Dim sql As String
        Dim myConnection As SqlCeConnection
        myConnection = New SqlCeConnection("Data Source=E:\sasitornpro\sasitornpro\MyDatabase#1.sdf;")
        myConnection.Open()
        Dim dt As New DataTable
        Dim myCommand As SqlCeCommand = myConnection.CreateCommand()
        sql = "SELECT product_brand FROM product GROUP BY product_brand"
        myCommand.CommandText = sql
        reader = myCommand.ExecuteReader()
        Dim autocomp As AutoCompleteStringCollection = New AutoCompleteStringCollection()
        Dim name As String
        While (reader.Read())
            name = reader("product_brand").ToString()
            autocomp.Add(name)
            ComboB.Items.Add(name)
            reader.Close()
        End While
        ComboB.AutoCompleteCustomSource = autocomp
    End Sub
    Private Sub BtSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtSave.Click
        If Me.TxtId.Text = "" Then
            MessageBox.Show("กรุณาใส่รหัสสินค้า ")
            Me.TxtId.Focus()
            Exit Sub
        End If

        If Me.TxtName.Text = "" Then
            MessageBox.Show("กรุณาใส่ชื่อสินค้า ")
            Me.TxtName.Focus()
            Exit Sub
        End If
        If Me.TxtUnit.Text = "" Then
            MessageBox.Show("กรุณาใส่สินค้าในสต็อค")
            Me.TxtUnit.Focus()
            Exit Sub
        End If
        If Me.ComboB.Text = "" Then
            MessageBox.Show("กรุณาเลือกยี่ห้อสินค้า")
            Me.ComboB.Focus()
            Exit Sub
        End If

        Dim myConnection As SqlCeConnection
        'myConnection = New SqlCeConnection("Data Source =" + (System.IO.Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().GetName().CodeBase) + "\Database1.sdf;"))
        myConnection = New SqlCeConnection("Data Source=E:\sasitornpro\sasitornpro\MyDatabase#1.sdf;")
        myConnection.Open()
        Dim myCommand As SqlCeCommand = myConnection.CreateCommand()
        myCommand.CommandText = "INSERT INTO [product] ([product_id], [product_name],[unitinstock],[product_brand]) VALUES  " & _
        " ('" & Me.TxtId.Text & "','" & Me.TxtName.Text & "' ,'" & Me.TxtUnit.Text & "','" & Me.ComboB.Text & "') "
        myCommand.CommandType = CommandType.Text
        myCommand.ExecuteNonQuery()
        myConnection.Close()


        MessageBox.Show("อัพเดทข้อมูลสำเร็จ")

        Me.Hide()
        Dim f As New FormProduct
        f.Show()


    End Sub

    Private Sub BtExit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtExit.Click
        Me.Hide()
        Dim f As New FormProduct
        f.Show()

    End Sub

End Class