我正在使用带有 MVVM 模式的 Visual Studio 2012 Ultimate 中的可移植类库。
当我在 ViewModel 中添加“使用”以引用 .NET 4 .dll 时，它说：
The type or namespace name 'prgTest' could not be found (are you missing a using directive or an assembly reference?)
附加信息：
The primary reference "MyDll" could not be resolved because it has an
indirect dependency on the framework assembly "mscorlib, Version=4.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089" which could not be resolved in the
currently targeted framework. ".NETFramework,Version=v4.0,Profile=Client". To resolve
this problem, either remove the reference "MyDll" or retarget your
application to a framework version which contains "mscorlib, Version=4.0.0.0,
Culture=neutral, PublicKeyToken=b77a5c561934e089".
如何“修复” MyDll.dll 或使其与我的项目兼容？