我正在开发一个UWP应用程序，我正在使用Template10。我遵循本教程：https://docs.microsoft.com/en-us/windows/uwp/monetize/launch-feedback-hub-from-your-app我遵循每一步！ 在事件处理程序（feedbackButton_Click）中，给出此错误：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html xmlns="//www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
<meta http-equiv="Content-Language" content="en-us" />
<link rel="shortcut icon"
href="//dnassets-mauganscorp.netdna-ssl.com/images/favicon.ico" />
<link rel="search" type="application/opensearchdescription+xml"
title="Desktop Nexus" href="//www.desktopnexus.com/opensearch.xml">
...
...
此代码中的代码：'IAsyncOperation<bool>' does not contain a definition for 'GetAwaiter' and no extension method 'GetAwaiter' accepting a first argument of type 'IAsyncOperation<bool>' could be found (are you missing a using directive for 'System'?)
我不明白这个错误，我做错了什么？