visual studio 2012 - Install-Package : Unable to find package 'FeatureToggle.Core' -

when trying install featuretoggle package manager console, below eror coming up.

this happening in vs 2012.

pm> install-package featuretoggle.core install-package : unable find package 'featuretoggle.core'. @ line:1 char:1 + install-package featuretoggle.core + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + categoryinfo : notspecified: (:) [install-package], invalidoperationexception + fullyqualifiederrorid : nugetcmdletunhandledexception,nuget.powershell.commands.installpackagecommand

i able

install-package featuretoggle 

make sure have chosen "all" package source dropdown in console.