我正在尝试在Xamarin Visual Studio中创建一个新的应用程序。我已经安装了Visual Studio 2017＆amp;后来的Xamarin包。现在，在创建跨平台应用程序时，我得到了三个弹出错误消息＃
第一个
The 'XamarinShellPackage' package did not load correctly.The problem may have been caused by a configuration change or by the installation of another extension. You can get more information by examining the file 'C:\Users\TestNameHere\AppData\TestName\Microsoft\VisualStudio\15.0_5c236eb4\ActivityLog.xml'.
Restarting Visual Studio could help resolve this issue
第二
A problem was encountered creating the sub project 'App4.Droid'. Object reference not set to an instance of an object.
和最后一个
A problem was encountered creating the sub project 'App4.iOS'. The project file 'c:\users\nic\documents\visual studio 2017\Projects\App4\App4.iOS\App4.iOS.csproj' cannot be opened.
There is a missing project subtype.
Subtype: '{FEACFBD2-3405-455C-9665-78FE426C6842}' is unsupported by this installation.
任何人都可以建议我在安装过程中做错了什么？