NuGet integration

I'm having trouble with LINQPad in combination with our SonaType Nexus Repository. I've configured our NuGet repositories in LINQPad exactly the same way as in NuGet / VisualStudio (besides, it would be great if LINQPad simply users the %APPDATA%\NuGet\NuGet.Config) and I always receive an error:

NuGet.Core threw an exception: The remote server returned an error: (400) Bad Request

There's no further information (e.g. which request failed) ...

Any ideas how to solve this?

Regards,
Daniel