Xamarin.Forms DLL cannot be installed

Hi Everyone,

I created a Blank App(Xamarin.Forms Portable ) project in Visual studio Professional 2012. When the project was being created, I saw an error that said Xamarin.Forms could not be reference. I ignored and created the project anyway. I finally tried using nuget in VS and I had this error below.

Could not install package 'Xamarin.Forms 1.2.3.6257'. You are trying to install this package into a project that targets
'portable-win+net45+wp80+MonoAndroid10+Xamarin.iOS10+MonoTouch10', but the package does not contain any assembly references or content files that are compatible with that
framework. For more information, contact the package author

Could anybody help me out as to the way forward in solving this

Thanks