Try
            con = New SqlConnection(conString)
            con.Open()
            MessageBox.Show("Offen")
 
            da = New SqlDataAdapter("SELECT Kategorie,Unterkategorie, Fehler," & _
              "Ursache FROM dbo.Hallo ", con)
            da.Fill(dtb)
            DataGridView1.DataSource = dtb
 
            da.SelectCommand.CommandText = "SELECT Kategorie " & _
                                        "FROM dbo.Hallo"
            da.SelectCommand.CommandType = CommandType.Text
 
            dt = New DataTable("")
            ds.Tables.Add(dt)
 
            da.Fill(dt)
 
 
            Dim Zeile As DataRow
            For I = 0 To dt.Rows.Count - 1
                Zeile = dt.Rows(I)
                ComboBox1.Items.Add(Zeile.Item(0))
            Next
 
 
 
 
 
        Catch ex As Exception
            MessageBox.Show(ex.Message)
 
        End Try