I'm using a WebDropDown and posting back with OnSelectionChanged.  The AutoComplete is no longer working properly because OnSelectionChanged causes a postback every time you type a character into the WebDropDown.  How do I make AutoComplete work properly when using OnSelectionChanged?

<ig:WebDropDown
    ID="wdd_AddAgent"
    Width="250px"
    OnPreRender="ClientFiltering_PreRender"
    EnableAutoCompleteFirstMatch="false"
    DropDownContainerHeight="300px"
    EnableViewState="true"  
    EnableAutoFiltering="Server"
    OnSelectionChanged="Populate_Default_Commission"  
    AutoPostBackFlags-SelectionChanged="On"
    runat="server">
</ig:WebDropDown>