Can't change the selected option

I have a data-bound dropdown,

<asp:DropDownList ID="cmbType" Runat="server" AutoPostBack="False" data-bind="value: moveType">
  <asp:ListItem Value="">-- Please Select --</asp:ListItem>
  <asp:ListItem Value="0">Car</asp:ListItem>
  <asp:ListItem Value="1">Air</asp:ListItem>
</asp:DropDownList>

      

        
        
        
      

    

When the page is loaded, by default (as I understand the first option is selected). The problem is that I cannot change this choice at all.

I've tried doing other things:

$('#cmbType option[value=' + d.Type + ']').attr("selected", "selected");

      

        
        
        
      

    

or

$("#cmbType").val(d.Type);

      

        
        
        
      

    

or

var viewModel = {
  this.moveType = ko.observable(d.Type);

};
ko.applyBindings(new ViewModel());​

      

        
        
        
      

    

d.Type = 0 or 1.

In fact, all options work. They change the visible value to the selected one (Car or Air), but when I try to get the selected value, I get value = "" (- Select -).

What happens when the dropdown shows that one of the options is selected (Car or Air), but the actual option selected is still (- Please Select -)?