Before running any of the end solutions provided in this Hands-on lab you need to ensure NuGet Package Restore is enabled. 

1. Click the "Tools" menu and select "Options".
2. In the "Options" dialog, select the "Package Manager" settings group.
3. Ensure the checkbox labeled "Allow NuGet to download missing packages during build" is checked.

For more information see: http://docs.nuget.org/docs/workflows/using-nuget-without-committing-packages