Insert Dropdown selection into FormView textbox (VB)

Hi all,
I struggling trying to insert the value I select from a "DropDownList1" country list into a TextBox inside a FormView1. I have tried the following but It wont insert the text:
I also tested on a textbox1 outside the FormView1 and it works but just after clicking Cancel or Inser in the formView1.
Any Ideas??

Protected Sub SelectedIndexChanged(ByVal sender As Object, ByVal e As EventArgs) Handles DropDownList1.SelectedIndexChanged Dim countrybox As TextBox = TryCast(FormView1.FindControl("CountryNameTextBox"), TextBox) countrybox.Text = DropDownList1.SelectedItem.Value 'TextBox1.Text = DropDownList1.SelectedItem.Text End Sub
Thanks in advance,

...