Why does GridView not showing data on Paging Index Changed?

I have a GridView that shows particular data and records when I click Generate button.

My problem is that when I click for the next page of the GridView list the Gridview will be lost, I don't think the data will be lost too, I guess the GirdView just doesn't show it.

Can you please help me with this problem. I'm not the one who first create this website and I tried all the things that I know for this problem, I also searched for a solutions in the internet with no luck. So I hope someone can tell me why is the GridView not showing after clicking the next page.

Here's the code for the Page_Load

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
    userid = IIf(SessionHandler.UserID = "", User.Identity.Name.ToUpper, SessionHandler.UserID)

    V3Substance.Attributes.Add("onfocus", "javascript:if (this.value=='Substance Cas Number') { this.value = ''; }")
    V3Substance.Attributes.Add("onblur", "javascript:if (this.value=='') { this.value = 'Substance Cas Number'; }")

    If Not Page.IsPostBack Then
        V1Division.DataSource = GetDivision()
        V1Division.DataBind()

        V1BR.Items.Clear()
        V1BR.DataSource = GetBusinessRule(V1Division.Text)
        V1BR.DataBind()

        MultiView1.ActiveViewIndex = 0
        Panel1.DefaultButton = "V1Generate"
    End If
End Sub

Here's the code for GridView1_PageIndexChanging

Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) Handles GridView1.PageIndexChanging
    Dim dt As DataTable = TryCast(GridView1.DataSource, DataTable)
    GridView1.DataSource = SortTable(dt)

    GridView1.PageIndex = e.NewPageIndex
    GridView1.DataBind()
End Sub

Here's the code for BindGridView

Private Sub BindGridview(ByVal query As String, ByVal countquery As String)
    ViewState.Add("Query", query)
    ViewState.Add("CountQuery", countquery)

    Dim count As Integer = 0

    If Description.Text = "1" Then
        ValidateFamily(query)
    Else
        DataSource = dbHelper.GetRecordDT(query)
    End If

    count = DataSource.Rows.Count

    'GridView1.DataSource = Nothing
    'GridView1.DataBind()
    'GridView1.PageIndex = 0

    GridView1.DataSource = DataSource
    GridView1.Visible = True
    GridView1.DataBind()

    ExportToExcel.Visible = IIf(count < 1, False, True)
    Panel1.Visible = IIf(count < 1, False, True)
    SetTotalResult(count)
End Sub

I also tried to put this code in Page_Load

If ViewState.Item("Query") <> Nothing Then
    BindGridview(ViewState.Item("Query"), ViewState.Item("CountQuery"))
End If

But the result is a problem also, it shows the GridView data list when I click the next page but when clicking the Generate button it's like this

or like this

Please help me with this. Thank you so much.

UPDATE

Okay so I put this code in Page_Load

If ViewState.Item("Query") <> Nothing Then
    BindGridview(ViewState.Item("Query"), ViewState.Item("CountQuery"))
End If

Then I put GridView1.Visible = True to GridView1_PageIndexChanging and when I click the next page it shows No Record Found only even if it fetched the data already.

So I've been doing this thing for a while now and thankfully I did it already. It took me a lot of different approach and solutions that didn't help me at all but thankfully, this one is correct now.

Code for Page_Load

 Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
            userid = IIf(SessionHandler.UserID = "", User.Identity.Name.ToUpper, SessionHandler.UserID)

            V3Substance.Attributes.Add("onfocus", "javascript:if (this.value=='Substance Cas Number') { this.value = ''; }")
            V3Substance.Attributes.Add("onblur", "javascript:if (this.value=='') { this.value = 'Substance Cas Number'; }")

            If Not Page.IsPostBack Then
                V1Division.DataSource = GetDivision()
                V1Division.DataBind()

                V1BR.Items.Clear()
                V1BR.DataSource = GetBusinessRule(V1Division.Text)
                V1BR.DataBind()

                MultiView1.ActiveViewIndex = 0
                Panel1.DefaultButton = "V1Generate"

                If ViewState.Item("Query") <> Nothing Then
                    BindGridview(ViewState.Item("Query"), ViewState.Item("CountQuery"))
                End If
            End If
End Sub

Code for GridView1_PageIndexChanging

 Protected Sub GridView1_PageIndexChanging(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewPageEventArgs) Handles GridView1.PageIndexChanging
            Dim dt As DataTable = TryCast(GridView1.DataSource, DataTable)
            GridView1.DataSource = SortTable(dt)

            GridView1.PageIndex = e.NewPageIndex
            'GridView1.DataBind()
            If ViewState.Item("Query") <> Nothing Then
                BindGridview(ViewState.Item("Query"), ViewState.Item("CountQuery"))
            End If
End Sub

I add

If ViewState.Item("Query") <> Nothing Then
                    BindGridview(ViewState.Item("Query"), ViewState.Item("CountQuery"))
                End If

in If Not Page.IsPOstBack for showing the record when selecting again in the DropDownList and in PageIndexChanging for showing record when clicking for the next page.