C# 无法从web配置读取自定义节

为什么我不能从我的web配置中读取此内容？当我使用App.config时，它工作得很好

FundGroups=null

Web.config：

<?xml version="1.0" encoding="utf-8"?>
<configuration>

<configSections>
    <section name="FundGroups" type="System.Configuration.NameValueSectionHandler" />
</configSections>

<FundGroups>
<add key="Group1" value="Value1" />
<add key="Group2" value="Value2" />
<add key="Group3" value="Value3" />
<add key="Group4" value="Value4" />
<add key="Group5" value="Value5" />
<add key="Group6" value="Value6" />
<add key="Group7" value="Value7" />
</FundGroups>


</configuration>

. 但是ConfigurationSettings.GetConfig似乎过时了，对我来说不起作用
使用ConfigurationSettings.GetConfig可能会重复那里的答案。GetConfig过时了。。。
<?xml version="1.0" encoding="utf-8"?>
<configuration>

<configSections>
    <section name="FundGroups" type="System.Configuration.NameValueSectionHandler" />
</configSections>

<FundGroups>
<add key="Group1" value="Value1" />
<add key="Group2" value="Value2" />
<add key="Group3" value="Value3" />
<add key="Group4" value="Value4" />
<add key="Group5" value="Value5" />
<add key="Group6" value="Value6" />
<add key="Group7" value="Value7" />
</FundGroups>


</configuration>