无法保存对配置文件的更改

我一直在关注这个堆栈溢出主题。一切都在阅读方面起作用。我得到了一个集合，我把它转换成一个章节内容的字典。我将此发布到其他项目。当我试图保存修改后的节条目时，就会出现问题。其中一个外部项目发送了一个键/值对，我需要将其保存到我的部分。这是我的应用程序配置

     <?xml version="1.0" encoding="utf-8" ?>
     <configuration>
        <configSections>
           <section name="fileEnvironmentSection" type="MyApp.Infrastructure.Configuration.FileEnvironmentSection, MyApp.Infrastructure"/>
        </configSections>
        <fileEnvironmentSection>
           <fileEnvironment>
             <add key="TestEntry1" value="A nice value"/> 
             <add key="TestEntry2" value="Another value"/> 
            </fileEnvironment>
        </fileEnvironmentSection>
     </configuration>

以下是与配置部分交互所需的三层类型。

     using System.Configuration;
     namespace SlamDunk.Infrastructure.Configuration {
        public class FileEnvironmentSection : ConfigurationSection {
           [ConfigurationProperty("fileEnvironment", IsDefaultCollection = false)]
           [ConfigurationCollection(typeof(FileEnvironmentCollection), AddItemName = "add", ClearItemsName = "clear", RemoveItemName = "remove")]
           public FileEnvironmentCollection FileEnvironmentList {
              get { return (FileEnvironmentCollection)base["fileEnvironment"]; }
           }
        }
     }

     using System.Configuration;
     namespace SlamDunk.Infrastructure.Configuration {
        public class FileEnvironmentCollection : ConfigurationElementCollection {
           public FileEnvironmentElement this[int index] {
              get { return (FileEnvironmentElement)BaseGet(index); }
              set {
                 if(BaseGet(index) != null) BaseRemoveAt(index);
                 BaseAdd(index, value);
              }
           }
           public void Add(FileEnvironmentElement fileEnvironmentElement) { BaseAdd(fileEnvironmentElement); }
           public void Clear() { BaseClear(); }
           protected override ConfigurationElement CreateNewElement() { return new FileEnvironmentElement(); }
           protected override object GetElementKey(ConfigurationElement element) { return ((FileEnvironmentElement)element).Key; }
           public void Remove(FileEnvironmentElement fileEnvironmentElement) { BaseRemove(fileEnvironmentElement.Key); }
           public void Remove(string key) { BaseRemove(key); }
           public void RemoveAt(int index) { BaseRemoveAt(index); }
        }
     }

     using System.Configuration;
     namespace SlamDunk.Infrastructure.Configuration {
        public class FileEnvironmentElement : ConfigurationElement {
           private const string appConfigDefaultString = "missing";
           private const string _appConfigNameKey = "key";
           private const string _appConfigNameValue = "value";
           public FileEnvironmentElement() { }
           public FileEnvironmentElement(string key, string value) {
              Key = key;
              Value = value;
           }
           [ConfigurationProperty(_appConfigNameKey, DefaultValue = appConfigDefaultString, IsRequired = true, IsKey = true)]
           public string Key {
              get { return (string)this[_appConfigNameKey]; }
              set { this[_appConfigNameKey] = value; }
          }
           [ConfigurationProperty(_appConfigNameValue, DefaultValue = appConfigDefaultString, IsRequired = true, IsKey = false)]
          public string Value {
             get { return (string)this[_appConfigNameValue]; }
             set { this[_appConfigNameValue] = value; }
          }
        }
     }

这是我用来保存键/值更改的代码。

     var appConfiguration = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
     var fileEnvironmentSection = appConfiguration.GetSection("fileEnvironmentSection") as FileEnvironmentSection;
     var fileEnvironmentList = fileEnvironmentSection.FileEnvironmentList;
     fileEnvironmentList.Remove(key);
     var element = new FileEnvironmentElement(key, value);
     fileEnvironmentList.Add(element);
     //appConfiguration.Save(ConfigurationSaveMode.Modified);
     //fileEnvironmentSection.CurrentConfiguration.Save(ConfigurationSaveMode.Modified);
     fileEnvironmentList.CurrentConfiguration.Save(ConfigurationSaveMode.Modified);

我已经检查过了，更改如预期的那样出现在列表中。我已经试过两次有评论的保存呼叫加上最后一次。我想我正在获得FileEnvironmentSection的一个新实例，以避免ConfigurationManager缓存问题。每次测试运行后，我都会查看MyApp.exe.config，但没有发现任何更改。我错过了一些东西，需要一些帮助才能弄清楚是什么。谢谢

appConfiguration.Save(ConfigurationSaveMode.Modified, true);
appConfiguration.Save(ConfigurationSaveMode.Full, true);