当我构建项目时,我从DNX Core 5.0收到错误,找不到命名空间：

All packages are already installed and there is nothing to restore.
NuGet package restore finished.
1>------ Build started: Project: WebApplication3,Configuration: Debug Any cpu ------
1>C:\Projects\WebApplication3\src\WebApplication3\MessageServices.cs(5,7,5,15): DNX Core 5.0 error CS0246: The type or namespace name 'Mandrill' could not be found (are you missing a using directive or an assembly reference?)
1>
1>  Build Failed.
1>           0 Warning(s).
1>           1 Error(s).
1>
1>  Time elapsed 00:00:00.1404086
1>
========== Build: 0 succeeded or up-to-date,1 Failed,0 skipped ==========

我试图将它添加到project.json中的dnx451框架,而不是添加为全局依赖项,结果相同.

"frameworks": {
    "dnx451": {
        "dependencies": {
            "Mandrill": "1.3.1"
        }
    },"dnxcore50": { }
},

甚至可以在ASP.NET 5中使用.NET 4包吗？如果是这样,需要什么？