Combobox issues

[kevin hash]

Hi, I am making a project to see al my dvd's plus their information in a windows form with ado.net.

Now I've made a form that has the design like the picture "design.jpg". On this picture you can also see the datasources and tables I use.

The structure of my dataset is like on this picture: "dataset.jpg"

This is my code:

Public Class frmDVDcollectie
 
    Private Sub frmDVDcollectie_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'TODO: This line of code loads data into the 'DtsMuziekcollectie.tblCategorieen' table. You can move, or remove it, as needed.
        Me.objTblCategorieenTableAdapter.Fill(Me.objDtsMuziekcollectie.tblCategorieen)
        'TODO: This line of code loads data into the 'DtsMuziekcollectie.tblDVDInhoud' table. You can move, or remove it, as needed.
        Me.objTblDVDInhoudTableAdapter.Fill(Me.objDtsMuziekcollectie.tblDVDInhoud)
 
        Vullen()
 
    End Sub
 
    Private Sub Vullen()
        Dim dtvDVDInhoud As DataView
 
        dtvDVDInhoud = objDtsMuziekcollectie.tblDVDInhoud.DefaultView
        dtvDVDInhoud.RowFilter = "CategorieID = " & cboCategorie.SelectedValue.ToString
        dtvDVDInhoud.Sort = "DvdID ASC"
 
        objTblDVDInhoudBindingSource.DataSource = dtvDVDInhoud
        Me.objTblDVDInhoudBindingSource.MoveFirst()
 
 
    End Sub
 
    Private Sub cboCategorie_SelectedIndexChanged_1(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboCategorie.SelectedIndexChanged
        If Not cboCategorie.SelectedValue Is Nothing Then
            Vullen()
        End If
    End Sub
 
    Private Sub btnVorige_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnVorige.Click
        Me.objTblDVDInhoudBindingSource.MovePrevious()
    End Sub
 
    Private Sub btnVolgende_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnVolgende.Click
        Me.objTblDVDInhoudBindingSource.MoveNext()
    End Sub
 
    Private Sub btnEerste_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEerste.Click
        Me.objTblDVDInhoudBindingSource.MoveFirst()
    End Sub
 
    Private Sub btnLaatste_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLaatste.Click
        Me.objTblDVDInhoudBindingSource.MoveLast()
    End Sub
 
End Class

The problem I have is that when I compile the project that I can perfectly change the categoriebut when I have changed the categorie, the I've selected is there twice and the categorie that is one step above the one I've selected is gone. How can I make sure that all my categories keep standing their on there place?

Greetings
Hash