dropdown in a gridview ?

[etsoft]

Hi,

i'm trying to get a dropdown in a filled datagrid, the code i have so far is :

 Dim mycommand3 As New MySqlCommand
        Dim myadapter3 As New MySqlDataAdapter
        Dim sql As String
        Dim mydata3 As New DataTable
        sql = "select Lasnummer,diameter1 from lisl_gegevens_new where Isonummer ='" & isonr & "' order by lasnummer;"
        Connectdb()
        mycommand3.Connection = conn
        mycommand3.CommandText = sql
        myadapter3.SelectCommand = mycommand3
        myadapter3.Fill(mydata3)
        ListLas.lassen.DataSource = mydata3

        Dim dgvcolumn As New DataGridViewComboBoxColumn

        For a As Integer = 1 To 10
            dgvcolumn.Items.Add(CStr(a))
        Next a

        dgvcolumn = ListLas.lassen.Columns(1)

On the last command i'm getting an error :

Unable to cast object of type 'System.Windows.Forms.DataGridViewTextBoxColumn' to type 'System.Windows.Forms.DataGridViewComboBoxColumn'.

Could some explain to me how this is done correctly. The datagrid itself is filled correctly.

Thanks in advance
Erwin