Why is the background image body 2 pages if the tablix record is more than one row in RLDC with VB.N

Dear Sir,

I'm using background image body but if the tablix record is more than one row make 2 page in Rdlc with VB.NET.

Is there something wrong or is there something I should set?, but if the Tablix record is only one, then the result is still 1 page

Please Guide me

Thanks

Link screenshot result and background image

 code in form 1

Imports Microsoft.Reporting.WinForms

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim form2 = New Form2()
        Dim rds = New ReportDataSource("DataSet1", Me.DataGridView1.DataSource)
        form2.ReportViewer1.LocalReport.DataSources.Clear()
        form2.ReportViewer1.LocalReport.DataSources.Add(rds)
        form2.ReportViewer1.LocalReport.ReportEmbeddedResource = "WindowsApplication1.Report1.rdlc"
        form2.ReportViewer1.RefreshReport()
        form2.ShowDialog()
    End Sub
End Class

 code in form2

Public Class Form2
    Private Sub Form2_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    End Sub
End Class

 Code Object class model

Public Class Product
    Public Property Productname() As String
    Public Property Qty() As Double
End Class