EXT:C#组合框设置来自Codebehind的值

我有这个组合框：

<ext:ComboBox runat="server" ID="cmbEmailVer"  FieldLabel="Email verification"  Width="420" ForceSelection="true" EmptyText="Select a value..." OnDirectChange="cmbEmailVer_DirectChange" OnLoad="cmbEmailVer_Load" >
     <Items>
           <ext:ListItem Text="Yes" Value="1" />
           <ext:ListItem Text="No" Value="0" />
     </Items>
</ext:ComboBox>

---

但是，即使我可以通过断点看到它从codebehind设置了正确的值，应用程序中的组合框也不会改变

使用

SelectedIndex

if (em != null)
{
   string s = (em.login_verify_email ? 1 : 0).ToString();
   cmbEmailVer.SelectedIndex = cmbEmailVer.Items.IndexOf(s); 
}
else
{
   cmbEmailVer.SelectedIndex = cmbEmailVer.Items.IndexOf("1") 
}

if (em != null)
{
   string s = (em.login_verify_email ? 1 : 0).ToString();
   cmbEmailVer.SelectedIndex = cmbEmailVer.Items.IndexOf(s); 
}
else
{
   cmbEmailVer.SelectedIndex = cmbEmailVer.Items.IndexOf("1") 
}