<ext:TextField ID="txt_SiteUrl" runat="server" FieldLabel="网站地址" AnchorHorizontal="%60"
                        IsRemoteValidation="true">
                        <RemoteValidation OnValidation="CheckField" ValidationEvent="blur">
                        
                        </RemoteValidation>
                    </ext:TextField>

  <ext:Button ID="BtnSave" runat="server" Text="保存">
                <Listeners>
                    <Click Handler="if(!#{WebFrom}.getForm().isValid()){Ext.Msg.alert('消息', '请填完整网站信息!');return false;}" />
                </Listeners>
                <DirectEvents>
                    <Click OnEvent="Btn_Save">
                        <Confirmation Message="确定要保存吗？" Title="提示" ConfirmRequest="true" />
                        <EventMask Msg="正在执行保存操作,请稍后??" ShowMask="true" />
                    </Click>
                </DirectEvents>
            </ext:Button>
Click the Save button does not verify whether it is valid, why?