Ext.Net 1.x_Ext.Net.Combox选择触发事件

<DirectEvents>
<Select  OnEvent="ChangeCurrency"></Select>
</DirectEvents>

protected void ChangeCurrency(object sender, DirectEventArgs e)
{

if (this.cbxCurrency.SelectedItem.Value.Trim() == "RMB")
{
this.txtRate.Text = "1.000000";
}
else
{
ZMQuotation zmq = new ZMQuotation();
zmq.Currency=this.cbxCurrency.SelectedItem.Value.Trim();
ZMQuotationManager zmqm=new ZMQuotationManager ();
this.txtRate.Text =zmqm .GetRate(zmq);
}
}