comboBox will not allow user to type in it unless dropdown control is first activated by click

hello,

using combobox... simple example:

<asp:ComboBox ID="yadayada" runat="server"
  CssClass="ComboBoxInsideModalPopup"
  DropDownStyle="DropDownList"
  AutoCompleteMode="SuggestAppend"
  CaseSensitive="false"><asp:ListItem Text="One" Value="One"></asp:ListItem><asp:ListItem Text="Two" Value="Two"></asp:ListItem><asp:ListItem Text="Three" Value="Three"></asp:ListItem></asp:ComboBox>

it's supposed to be just like a combobox in winForms applications... I need to create a web form very efficient for data input via keyboard, so the combobox *should* be perfect for tabbing into from previous field, then just start typing and the AutoCompleteMode should kick in and start showing closest matches. I specifically need to only allow values in the list. However after tabbing into the combobox from the previous field I start to type and nothing appears... however if I click with the mouse the control to show the list, the list shows, *then* if I click inside the area to type and start typeing it works. If I change the DropDownStyle to Dropdown, it works exactly as I expect when tabbing into the control from the previous control, but setting to Dropdown also allows the user to enter values not in the list.

what's going on? Major disappointment. I've already installed latest version of the toolkit (January 2013 release), using VS 2008, framework 3.5.