Не изменяется значение в DataGridView

Imports System.Data.SqlClient
 
Public Class Form1
    Dim departnumber As Integer = 25
    Dim combobox1 As New ComboBox()
    Dim connection As New SqlConnection("Data Source=bla;Initial Catalog=blabla;Persist Security Info=True;User ID=sa;Password=blablabla")
    Dim querystring As String = "select ID_DEP, DeptName from dbo.depart"
    Dim depstring As String = "select ID_USER, FirstNAme, SecondName, ThirdName, EmpStatus, Dep_ID from dbo.personel where Dep_ID="
    Dim adapter As SqlDataAdapter = New SqlDataAdapter(querystring, connection)
    Dim depadapter As SqlDataAdapter = New SqlDataAdapter(depstring + Str(departnumber), connection)
    Dim dataset1 As DataSet = New DataSet
    Dim depart As DataTable = dataset1.Tables.Add("Depart")
    Dim person As DataTable = dataset1.Tables.Add("personel")
    Dim label1 As New Label()
 
 
 
 
 
 
    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        connection.Open()
        If connection.State <> ConnectionState.Open Then
            MessageBox.Show("NotConnected")
            Exit Sub
        End If
        adapter.Fill(dataset1, "depart")
        combobox1.Height = 400
        combobox1.Width = 400
        combobox1.DataSource = depart
        combobox1.DisplayMember = "DeptName"
        combobox1.ValueMember = "ID_DEP"
        AddHandler combobox1.SelectedValueChanged, AddressOf ComboBox1_SelectedValueChanged
        Me.Controls.Add(combobox1)
        label1.Location = New System.Drawing.Point(454, 203)
        label1.Size = New System.Drawing.Size(39, 13)
        label1.BorderStyle = BorderStyle.Fixed3D
        Me.Controls.Add(label1)
 
        departnumber = combobox1.SelectedValue
        label1.Text = Str(departnumber)
        depadapter.Fill(dataset1, "personel")
        DataGridView1.DataSource = dataset1.Tables("personel")
        Me.Controls.Add(DataGridView1)
 
    End Sub
 
 
 
    Private Sub ComboBox1_SelectedValueChanged(ByVal sender As Object, ByVal e As System.EventArgs)
 
        departnumber = combobox1.SelectedValue
        label1.Text = Str(departnumber)
        dataset1.Tables("personel").Clear()
        depadapter.Fill(dataset1, "personel")
 
    End Sub
 
End Class