C# - 从 WebResponse 获取响应

我正在尝试下载放置在互联网上的RSS提要的XML源代码，但是当我的进程到达WebResponse语句（第二行波纹管）时，进程停止，接下来什么都没有发生。没有错误，没有例外或类似的东西。我等了几十分钟，仍然没有任何反应。

WebRequest request = WebRequest.Create(source.Url);
WebResponse response = await request.GetResponseAsync(); // at this line it stops
Stream receiveStream = response.GetResponseStream();
StreamReader readStream = new StreamReader(receiveStream);
string xml = readStream.ReadToEnd().Trim();
readStream.Dispose();
response.Dispose();

知道是什么原因造成的吗？

编辑：

public static async Task<string> GetContent(string uri)
{
    WebRequest request = WebRequest.Create(url);
    using (WebResponse response = await request.GetResponseAsync().ConfigureAwait(false))
    {
        Stream receiveStream = response.GetResponseStream();
        StreamReader readStream = new StreamReader(receiveStream);
        return readStream.ReadToEnd().Trim();
    }
}
public async Task<ObservableCollection<Source>> GetArticlesFromSource()
{
    sourceDefinitions = await GetSourceDefinitions();
    string imageFolderName = "ArticleImages";
    string imageFolderPath = localFolder.Path + "''" + imageFolderName;
    StorageFolder imageFolder = await localFolder.CreateFolderAsync(imageFolderName, CreationCollisionOption.ReplaceExisting);
    foreach (var source in sourceDefinitions)
    {
        if (source.Selected == "true")
        {
            ObservableCollection<Article> articlesStep1 = new ObservableCollection<Article>();
            /*WebRequest request = WebRequest.Create(source.Url);
            WebResponse response = await request.GetResponseAsync();
            Stream receiveStream = response.GetResponseStream();
            StreamReader readStream = new StreamReader(receiveStream);*/
            string xml = await GetContent("http://www.honzachalupa.cz/").ConfigureAwait(false);
            Debug.WriteLine(xml);
            ...