NuGet package now showing up in Package Manager Console in VS2015

Hello,

We are setting up our TeamCity as a NuGet server.

After pushing the package .nupkg to build artifacts, we can see it from VS2010 and VS2012 Package Manager Console. But in VS2015 Package Manager Console, it shows 'No packages found in the current package source.' Please see attached screenshots.

Do you know what might cause this difference?

Thanks,

Ge