OnClientSelectedIndexChanged 在下拉列表更改时未触发

问：

更改下拉所选值时，我的 OnClientSelectedIndexChanged javascript 函数未触发。我在 javascript 函数的第一行放置了一个断点，但它从未到达。

<telerik:RadCodeBlock ID="RadCodeBlock1" runat="server">       
        <script type="text/javascript" >
            function ddl_AutoSchedule_SelectedIndexChanged(sender, eventargs) {
                var date_DueDate = $find("#date_DueDate");
                var date_PlannedStart = $find("#date_PlannedStart");
                var date_PlannedFinish = $find("#date_PlannedFinish");
                date_DueDate.value = Now.AddDays(sender.value);
                date_PlannedStart.value = Now.AddDays(0);
                date_PlannedFinish.value = Now.AddDays(sender.value);
            }
        </script>
    </telerik:RadCodeBlock>

还有我的下拉列表：

<telerik:RadDropDownList ID="ddl_AutoSchedule" runat="server" Enabled="false" AutoPostBack="True" OnClientSelectedIndexChanged="ddl_AutoSchedule_SelectedIndexChanged">
  <Items>
     <telerik:DropDownListItem Value="0" Text="Select a Schedule" />
     <telerik:DropDownListItem Value="30" Text="30 Days" />
     <telerik:DropDownListItem Value="45" Text="45 Days" />
     <telerik:DropDownListItem Value="60" Text="60 Days" />
     <telerik:DropDownListItem Value="90" Text="90 Days" />
     <telerik:DropDownListItem Value="120" Text="120 Days" />
     <telerik:DropDownListItem Value="180" Text="180 Days (6 Months)" />
     <telerik:DropDownListItem Value="270" Text="270 Days (9 Months)" />
     <telerik:DropDownListItem Value="365" Text="365 Days (1 Year)" />
  </Items>
</telerik:RadDropDownList>